What better way to start Ash's moments of awesome than with his first moment of awesome? Episode 1 has him protecting Pikachu, who at the time didn't like him very much, from a flock of angry Spearow, standing them down and awaiting a Peck-filled death. Not only was this probably one of the most iconic scenes from the anime, but it also went on to cement Ash's Brass Balls. It also led to Pikachu's first moment of awesome. And of course, the speech Ash gives before the above moment:
Ash: "Spearows! Do you know who I am!? I am Ash, from the town of Pallet! I'm destined to become the world's number one Pokémon master! I can't be defeated by the likes of you. I'm going to capture and defeat you all! You hear me!? Pikachu, go inside the Poké Ball, it's the only way!" (Lightning strikes, the Spearows all charge at Ash) Ash:"Come and get me!"
Ash rushing into a burning building to save Erika's beloved Gloom. Special mention to the fact that Ash was actually a little afraid of Erika's Gloom because of its foul smell, yet he pushes forward anyways and rescues it. Is it any wonder Erika gave him the Rainbow badge?
One of Ash's more interesting and subtle moments of awesome is a dialogue in "Showdown at the Po-ke Corral", which is late in the Indigo arc after Ash has earned his eighth badge. In the series' beginning, it was a repeated plot point that Ash got off to a bad start on his journey and for the longest time was behind his Pallet Town peers (of which there were at least three, including Gary). In this episode we find out that Ash and Gary are the only Pallet Town trainers still continuing their journey, as all the other trainers got off to good starts but couldn't keep up. Despite Ash's bad start and rather small Pokemon pool, it speaks volumes that he got this far with sheer determination that the other Pallet Town trainers didn't have.
The climax of "Pokemon Emergency!" where Ash and Pikachu blast Team Rocket off for the first time. Especially his line in the original Japanese version:
Ash: Don't look down on Pikachu for being a mouse. I'll show you me and Pikachu's true power!
Ash beats Drake and becomes Orange League Champion by playing the long game. He doesn't even expect Charizard to beat Dragonite; he expects him to wear it out, which he does. Good thing, too, as Pikachu has to do a lot more work in order to topple the creature.
His battle in the Johto League Conference, where he finally defeated his long time rival, Gary Oak. After the battle, the two actually rekindled their old friendship as well!
He was at his ballsiest when Primeape caught up with him. After being beat up several times by it when it was a Mankey, and running for his life after it thrashed Team Rocket and smashed through everything in its path, he ends up making eye contact by accident (the very thing that had sent it into a berserker rage before.) He finally decides to stop running and face it head-on, as a true trainer would, and with the help of Charmander, manages to catch it.
Ash defeating Professor Namba in "A Promise is a Promise".
Selflessly performing a Cooldown Hug when Chimchar goes out of control with Blaze. He also does this with Monferno, this time while engulfed in flames.
The moment that Ash strives to prepare to rematch Sabrina after his defeat by her on his first journey. He tries to get the psychic who saved him to tell him how to beat her, but the guy insists that he doesn't have a chance against psychic powers no matter what. To make his point, he keeps telekinetically sending Ash flying back off his feet and crashing into the ground. Each time, the kid gets right back up and keeps marching forward, keeps getting knocked down, and keeps getting back up and trying again, ignoring Brock desperately telling him to give up. Ash shocks the man when he eventually does resist his efforts to psychically push him back and is able to keep going forward. It may not be a battle, but it's such a perfect demonstration of how strong this kid's will and resolve really is, to say it's Awesome is an understatement.
Ash taking up the role of a mentor toward his new travelling companion, May, in the Advanced series. Him taking such a position proves that he is not a rookie anymore.
In "A Scare to Remember" when Pikachu has lost its memory and joined Team Rocket, Ash does a running jump onto Team Rocket's balloon as it's taking off, then climbs all the way up into the basket to get Pikachu back. Despite Pikachu being on their side, this causes a major Oh, Crap! reaction from Team Rocket, just from the ticked-off look on his face. He then manages to catch Pikachu in mid-air after its attack destroys the balloon. Even better, it's implied this show of determination (and his subsequent words to Pikachu) are what revives its memory.
Ash: Nobody's going to take... my best buddy!
In "Less Is Morrison", Team Rocket trap Ash and Morrison and make off with their Pokemon. The two resort to stopping Team Rocket with their own brute strength, improvising a "Take Down" to escape their cage and even battling Seviper and Cacnea by themselves.
One of the Battle Frontier episodes has Ash coming to battle Tucker. This is actually the first episode where we see that the world does recognize Ash as a great trainer. As he approaches it, he's spoken to by the press, and all of his accomplishments are announced when he finally makes it in.
On his return to Petalburg in "A Double Dilemma", Ash gets mobbed by Norman's slavering fans. He wallops the whole town, and nearly curb-stomps May as well (the fans are quick to call it her win when Torchic misses and KO's Ash himself, despite Taillow having barely been touched). And while the episode ends with Ash failing to win over the townspeople, Ash's response, "At least they like one of us" (the crowd was impressed by Pikachu's defeat of Team Rocket) was remarkably mature.
Ash's battle with Tucker in Tactics Theatrics. After spending most of it being curb-stomped by Tucker's superior strategy, Ash manages to put a move together where Corphish rides on Swellow's back, then jumps off when they get close. Swellow hits Tucker's Swampert with Aerial Ace while Corphish slams Arcanine right in the face with a Crabhammer, knocking them both out at once.
A minor one during Ash's four-on-four match against Brandon. Ash's Squirtle is blinded by Ninjask's Sand-Attack. His solution? Have Squirtle fire a Hydro Pump wildly into the air, allowing the water to crash back down on it and clean the sand out of its eyes. Very clever and resourceful. Nurse Joy even wrote it down, apparently seeing some kind of medical benefit to it.
Ash becoming an expert in creating new spectacular battling techniques and strategies, as well as furthering his knack of using the battlefield in his favor in the Diamond and Pearl saga. All of the instances he showcases these are not just mere display of him being an awesome Trainer, but also a milestone of just how far he has come in his journey and all of the experiences he had garnered up until that point. Case in point: Counter Shield.
The final battle between Ash and Paul in the Sinnoh League. All three parts of it. Arguably overthrowing Ash vs Gary as the greatest league match ever.
Turning his hat backwards for the first time since THE INDIGO LEAGUE.
Complain about Tobias being overpowered if you want, just consider this. Not only was Ash was the only one in the tournament who managed to KO Darkrai, he then followed it up with a KO against a second legendary Pokémon. Tobias needed Legendaries to beat Ash's team; Ash didn't need Legendaries to beat Tobias' team. In fact, it's stated outright that Tobias solo-ed ALL EIGHT GYMS with just Darkrai. On top of that, he solo-ed the finals with Darkrai, meaning Ash was the ONLY trainer to beat the legendary Pokemon.
It's what happens immediately after Ash turns his hat around that makes it his greatest moment: Ash has only one Pokémon left. Tobias has five, one of which is a Latios. Despite all this, Ash loudly declares that he still intends to win the battle. Despite his Character Development throughout Sinnoh making him a bit more level-headed, he's still got balls of steel.
If there was ever any doubt Ash was a better trainer than Paul, it right proper evaporated when he won the infamous match in the Tag Tournament. He had a scorched Turtwig under his command. Paul (who abdicated his role in the match) had his brutally wounded Chimchar. The opposition had a Metagross and a Zangoose (the latter of which Chimchar was rightly scared of). Ash turned the entire match around and won despite this handicap.
Ash's second battle with Lenora in Black and White. Anyone who battled Lenora in the games can testify to how difficult she can be. Ash's training combined with the way his strategies played off of hers showed character development. Over the course of 2 episodes he became a hard worker and showed his trademark spirit.
Ash's third battle with Trip, after losing to him twice, Ash shows Trip what he's really made of, after a rough start where Snivy is defeated by Servine, Ash's Oshawott battles against Trip's Timburr and after taking some hits cleverly uses Timburr's own strength against it sending it into its own timber via Water Gun. Then Ash's Tepig and Trip's Vanillite battle it out and it's pretty amazing, with Pokemon hitting each with attack after attack and being evenly matched, culminating in Tepig using Flame Charge to interrupt Vanillite's Icicle Spear and then Vanillite using Blizzard and both Pokemon collide and end up fainting, resulting in the match ending in a draw and Ash finally getting some respect from Trip.
Not even a day upon entering Kalos and he still manages to show how much balls he has. In the span of a day, he works with new companions Clemont and Bonnie along with Froakie to access the Prism Tower to help quell a rampaging Garchomp. Even when he is left with Pikachu and Froakie, he still makes use of resources and manages to get a hold of the dragon to destroy the device causing it pain while on top of the tower. Then, when his Pikachu falls off, he doesn't think twice and leaps off to get him without hesitation. In short order, he was willing to climb to the top of Prism Tower, calm down and help a pseudo-legendary dragon that was in agony, and was more than willing to possibly die to save his best friend, all while being filmed for all of Kalos to witness. Badass and heartwarming. This is also an awesome moment for the writers! As the episode shows, the above events happened without any development reset on Ash and Pikachu's part, unlike all other new seasons! At last, it looks like the writers nicely managed to keep Ash consistently badass!
Serena's Rescue Romance backstory establishes Ash's heroism from nearly half his current age, helping a lost young Serena out of the forest after she injured her leg.
In "Day Three Blockbusters" after Serena nearly falls off a cliff, Ash quickly grabs her hand. Though he fails to hold them both up, he manages to keep grip and skid all the way down the crevice to slow their fall. He injures his foot in the process, but Serena comes out unharmed.
Cooperating with Pikachu in perfect sync when the latter is blinded by Inkay's ink, even taking advantage of Wobbuffet's Mirror Coat to hit Inkay with a high-powered Thunderbolt.
Ash's fight with Hawlucha to catch it was pretty good. Ash didn't catch Hawlucha when it's fainted, but rather waited for it to be conscious. He then offers Hawlucha to join him, to which it agreed. The awesome part? Ash didn't throw a ball to it or anything. Nope - instead they did a fistbump with Ash holding a Pokéball. That's how Hawlucha accepted Ash as a trainer.
Ash's efforts to improve Froakie and Hawlucha's teamwork in the Trevenant episode. He saw that two of his Pokémon were not getting along, so his solution is to construct a training regimen to fix that, not to mention he takes none of their nonsense whenever they seem like they are about to start fighting again. His efforts come to fruition during the battle against Team Rocket when Froakie and Hawlucha finally perfect Super Flying Cut. There's also a minor moment right before that where Ash has Hawlucha use Flying Press against Jessie's Pumpkaboo. Naturally, it fails, but Ash reveals that he did this purpose to get Jessie and Pumpkaboo to let their guard down and immediately has Froakie launch a surprise attack.
During Ash's Coumarine Gym battle with Ramos, Frogadier is having trouble against Gogoat. Ash is starting to get frustrated, but then he remembers what Ramos told him about how not rushing his task will help him see things more clearly when he had to help Ramos with his gardening. Ash realizes how useful this gardening advice is for his current situation and he calms down, which allows him to start turning the tables in his battle.
His Lumiose Gym Battle against Clemont was basically one big Moment of Awesome. Aside from the fact that this was one of if not the most hyped gym battles of the series, Ash was pretty much in control for most of the battle. First, he had Pikachu defeat Bunnelby, effectively finishing what they started in XY 001, despite being caught off-guard by its newly-learned Wild Charge. Of course, that was just the tip of the iceberg. Clemont then sent out Heliolisk, which threw everyone off with its incredible speed. Goodra had trouble keeping up, so Ash substituted with Hawlucha to better match Heliolisk's speed. The awesome moment of this round came when Ash realized that despite its blinding speed, Heliolisk had to stop for a split second to use certain attacks. Ash was then able to get the jump on Heliolisk by having Hawlucha quickly use Hi Jump Kick at the exact moment Heliolisk stopped, no easy feat! And the final Moment of Awesome was the final round, Goodra vs. Luxray. Goodra is Ash's last Pokémon, and not only is it still paralyzed from Heliolisk's Thunder Wave, but Electric Terrain is still giving Luxray a big advantage. Ash quickly remembers Goodra's basic physiology and that its ability is Hydration, so he quickly resolves both obstacles by having Goodra use Rain Dance. The epic rest of the battle that ensues only adds to the awesomeness!
His 3-0 victory over Sawyer the episode after his victory at the Laverre Gym. In fact, not only did Ash wipe the floor with him, he gave him good advice while doing it!
Ash really shows how he can think on the fly in his gym battle against Olympia, changing his strategy multiple times on the spot. Talonflame and Frogadier go from not being able to land a single hit on the Meowstic to turning their own attacks against them.
During the group's encounter with Team Flare in Terminus Cave, at one point Bonnie is about to be hit by Drapion's Pin Missile, but Ash swoops in, grabs her, and runs to safety. He looks like a soldier rescuing a civilian.
Even if he and Greninja passed out at the end of it, Ash's battle against Diantha is perhaps his crowning achievement as a trainer, and one of the few times the writers actually allow him to show how skilled he should be by this point.
This needs elaboration. Up until this point in the show, the Elite Four and Champions had been portrayed as utterly dominant in any fight with a non-Elite. With Ash, Paul, and anyone but Alain getting a Curb Stomp Cushion at best. Ash's earlier battle with Diantha got the same result, and his rematch started off the same way. But after Greninja gets slammed by a Moonblast, Ash realizes that Gardevoir needs to make eye contact with Diantha in order to dodge as gracefully as it does. So he has Greninja use Water Shuriken to cover the ground with steam and then successfully land a strike with Cut when Gardevoir can't see Diantha's signal. After activating the transformation, Ash and Greninja push themselves further than they've ever gone before! Together, they land another hit on Gardevoir, force Diantha to Mega-Evolve her, break through her Reflect, and finally, complete the transformation and knock Gardevoir down with a MASSIVE Water Shuriken. As Gardevoir proceeded to faint after blasting off Team Rocket right after, that means that Ash came within ONE HIT of beating Diantha's Ace Pokemon. Until Ash fought Kukui in Alola, this was his finest hour as a trainer.
Just whenever Ash mimics his Greninja's movements when it's in its Ash-Greninja forme. It's among the rarest times where him being a badass is displayed even for a 10-year old kid.
Ash's entrance in the Kalos League is nothing short of awe-inspiring. He gets stopped in the hallway on the way to his first match by a trainer who was unable to gather eight badges and who wants to prove badges mean nothing and he's just as capable as league participants. Ash accepts his challenge and swiftly defeats his Furfrou with Pikachu while telling him that badges do have meaning and are proof of his growth as a trainer and as a person. As he resumes going towards the stadium, the other trainer tells him in tears that there are many like him who couldn't make it this far and asks Ash to win for all of them, which Ash promises. As he narrowly makes it to the battlefield right before being disqualified for forfeiting, Ash makes a big claim in front of the whole league about how he's going to win it all, making the crowd go wild. Then as the first match begins, Ash and Greninja go through their transformation, Ash Greninja dodges the opponent's Altaria's Draco Meteor and one-shots it with a single Water Shuriken, leaving the crowd and the announcer in disbelief. It is implied Ash Greninja swept the remaining two Pokémon with one attack each as the scene cuts to the scoreboard at the end of the day with the Furfrou trainer looking satisfied at Ash's victory. For reference, in the Sinnoh League, Tobias' Darkrai dodged Ash's Gible's Draco Meteor and proceeded to one-shot it. Ash is essentially becoming the Tobias of the Kalos League.
He pulls off a brilliant tactic in battle between his Pikachu and Sawyer's Aegislash in Kalos League semifinals. Noticing that Aegislash needs to return to its sheath to use King's Shield, he orders Pikachu to slam the ground with Iron Tail, sending all pieces of wood that were earlier cut by Aegislash flying. Then, Pikachu starts jumping on them at insanely high speed, dodging all attacks and moving into position to launch his own. Sawyer calls for King's Shield, but Pikachu reacts faster and knocks one of wood pieces into Aegislash's sheath, making it unable to return to Shield Forme and leaving it wide open for round-ending Thunderbolt.
Ash in the Kalos League final:
The mere fact that he managed to finally make it to the league final is nothing short of awesome. It shows that all of his experience and strategies have finally paid off.
By the time the first of the two parter final ends, Ash is winning the battle, having a worn down, yet battle hardened Pikachu as well as a fresh Goodra and Greninja to face Alain's Bisharp and Charizard.
Unfortunately, Pikachu is defeated rather quickly by Charizard, before he recalls it for Bisharp to face Goodra. Goodra puts up a good fight and Bisharp suffers major damage, but defeats Goodra with another Guillotine. Finally, Greninja comes and wipes the floor with Bisharp, leaving him to face Charizard. Greninja seems to have Charizard on the back foot, the pair powering up for the final battle, yet despite the type advantage, Greninja is defeated by Charizard's Blast Burn, while Water Shuriken fails to KO Charizard.
Say what you will about the controversy about the conclusion of the Kalos League, but Ash was still the runner up (furthest he had ever gotten in a league before) and he gave Alain a run for his money from start to finish. Alain's Charizard was said to be the Pokemon that swept through every Pokemon it fought against in all of the league's run. The fact that Pikachu and Ash-Greninja held their own and scored some good hits, and defeated all of Alain's other Pokemon on top of that, showed how close the fight was.
Take a good look at Charizard before Greninja faints: it staggers for a bit, meaning it had to steel itself to keep from fainting on the spot. That giant Water Shuriken clearly hurt more than it initially seemed.
Ash using the Bond Phenomenon to break free from Team Flare's shackles and facing down Lysandre. To elaborate, Ash and Greninja are restrained by their shackles and being tortured by Lysandre's drone-like devices, but Ash, despite the excruciating pain, gives a moving speech that snaps Alain out of his Heroic BSoD, then activates the transformation. This particular transformation generates a water column that envelops the entire Lumiose Tower, after which Ash and Greninja shatter their bonds and knock away the torture devices with the column of water. Alain is outright shocked, and Lysandre is visibly impressed. And he's basically telling Lysandre to shove it all the way.
Lysandre: Ash. I'm going to use your Bond Phenomenon for the sake of my world. I'll obtain the ability to become so strong even without a stone... I was so happy when I first saw it! It made me realize that Pokémon indeed have infinitely more potential. I desire that power too. This light is energy that is strong enough to control even Zygarde! Ash, and Greninja! Your power shall be under my control. Once this is over, you shall be mine! Ash:We'll never do as you say! Lysandre: You still fail to understand? Once this world is destroyed... You shall be the guide of the chosen people! Ash: We're never gonna become any of that! We're not ever going to change! Alain! I don't know what happened to you, but you go to stop all of this now! I don't care about you have done. I believe in the Alain that I know! I really care about this world! I care about the people and Pokémon who call this world home! And you won't destroy it, no way! (activates the transformation) Battle me, Lysandre!
Ash and Alain battle against Lysandre's Mega Gyarados, and while they have seven Pokemon in total, Gyarados doesn't even flinch, taking out over half in one or two hits. Only Ash-Greninja, Charizard X and Pikachu are left standing, but that doesn't stop Ash from pointing out how nobody will stop fighting; not one of them will give in to what Team Flare wants.
Ash: Lysandre, I don't care about how you hate this world! It belongs to everyone, people and Pokémon. Don't you talk about destroying it, changing it, saying tomorrow won't come! Tomorrow someone will meet someone important to them. Tomorrow someone will realize their dreams! Tomorrow someone will start their journey as a trainer. Tomorrow someone will heal their wounds. Everyone has their own tomorrow! What is the reason you get to take it from them? For all those people and Pokémon...I will fight at my absolute best!
Sun and Moon Ash actually learns how to use Z-Moves. Unlike in XY, he won't be without the new mechanic.
Just the fact that Ash was chosen by Tapu Koko himself. A very high praise in Alolan culture.
It takes only two episodes for Ash and Pikachu learn how to do Gigavolt Havoc from Tapu Koko. Their first use of the move leaves a sizable crater, and proves to be too much for the Z-Crystal to handle, as it shatters after only one use. That just inspires Ash to do the island challenge properly and get a crystal that won't break.
Ash's reasons for even attending the Pokémon School: he isn't going back to basics, rather he's learning new things that he wants to understand further to become a Pokémon Master. And as for any signs of Badass Decay? Well go on and ask all of Team Skull's Salandit, and Tapu Koko, and then try and say he's gotten weaker.
In SM005, Team Rocket are drifting well out of reach in the air and Pikachu cannot use his electric attacks on them or else he will risk also shocking the Water-type Pokémon that have been kidnapped. So what does Ash do? He has Pikachu use the hovering RotomDex as a stepping stone and cut the net open with Iron Tail!
SM007 has Ash taking a lot of scratches from Litten while getting it to the Pokémon Center, but that pales in comparison to taking Persian's attack to protect Stoutland. If that doesn't cement Ash's balls of steel, then the previous episode already did.
SM009: Ash participates in his first trial and has Pikachu and Rowlet outright mop the floor with the preceding Yungoos and Gumshoos. Then the Totem Gumshoos shows up and gives a bit of a bigger challenge, raising its stats so hardly anything can affect it, using Sand Attack to avoid their strikes, and eventually leaving Ash with just Pikachu standing. So what does Ash do in this situation? In typical Ash fashion, he does something that no one in the games would even think of doing and uses Gumshoos' Sand Attack against him by having Pikachu use the sand to hide its own figure and give Gumshoos a No-Holds-Barred Beatdown with Quick Attack, before finishing it off with a Thunderbolt! And after that whole ordeal, Gumshoos itself gives Ash the well-earned Normalium Z!
In SM010, Ash goes through his first Grand Trial with Hala and, even though it's implied that the Kahunas are on a whole other level from Gym Leaders, manages to win without a single Pokémon fainting! And no, Rowlet falling asleep after its match doesn't count.
To start, Ash sends his Rowlet against Hala's Crabrawler, normally his strongest Pokémon in the games. Crabrawler constantly tosses it around with Power-Up Punch and Brutal Swing, and even blocks Leafage with its own Bubble Beam despite not even being a water type. However, Rowlet still has its ability that allows it to sneak around about the Leafage and surprise people. When Ash remembers this, Rowlet quickly picks up the slack and lays an epic beatdown on Crabrawler, managing the win.
Square up next is Pikachu vs. Hariyama. The Arm Thrust Pokémon manages to be more than a match for Pikachu, blocking its fast movements with its own powerful Fake Out, Knock Off, and Arm Thrust. Despite this, Pikachu's nimble movements allow it to keep in the fight and outmaneuver Hariyama at several key points. Pikachu even manages to survive a hit from Hariyama's Belly Drum boosted All-Out Pummeling and is still as spry as ever! Pikachu finishes the fight by running circles around Hariyama with Quick Attack before knocking it down with Iron Tail, then they finish the job by performing the Breakneck Blitz, knocking Hariyama clear out of the ring! Tapu Koko is so impressed that, when Hala is about to give Ash the normal Fightinium Z, he swoops in and replaces it with an Electrium Z, thus Ash has fully earned his Z-Crystal from the first episode of the season.
We see the results of Ash obtaining Electrium Z with Ash's second use of Gigavolt Havoc in SM011. Poor, poor Team Skull.
In SM029 The group has a Morulull problem. His solution: stick the energy sucker on his head while eating to give it so much energy it won't go after them anymore. It works. Or to put it another way, Ash met a parasitic fungus and let it feed on him so they could be friends.
Ash vs. Misty in SM043:
While Pikachu is trapped within Mega Gyarados' combination of Hurricane and Rain Dance which has nullified Pikachu's Electric-type attacks, even rendering Thunderbolt moot from piercing through the column of water surrounding Pikachu. What does Ash do? He commands Pikachu to use Quick Attack to... climb through the hurricane by using the electricity as footing. This leaves Misty and the Alola cast shocked and Ash follows it by ending the match by having Pikachu use Gigavolt Havoc, defeating Misty's Mega Gyarados. The only one not surprised by it at all is Brock, who simply has an expression on his face that says "Yep, that's Ash for you all right."
When the battle is about to begin, Sophocles looks at the battlefield with little land and questions how anyone could fight on it. Ash grins and declares he will, and Pikachu immediately gets into the thick of it with enthusiasm and not a hint of hesitation. For those who miss Gym Battles, it's a nice reminder of how many they'd fought, and in how many different fields.
For extra points, Misty earlier mocked Ash over not defeating her and only getting his Cerulean Water Badge out of pity. It seemed to be Tempting Fate as straight after Ash outdoes Misty fair and square. Misty finally gave him his rematch and not only was it much more difficult than before, but he won despite the massive power disadvantage between Mega Gyarados and Pikachu.
During SM050, Ash foregoes Pokémon battling and just straight up body slams Faba himself to try and save Nebby from him. Considering how much of a jerk Faba is, no one's complaining. Even better, think about how many bad guys Ash has faced. Giovanni, Cyrus, Ghetsis, Lysandre. He faced them all despite them either wanting to control all Pokemon, create a new world, rule the world, or destroy everything respectively. All were grade A nutcases. But Faba? He allowed Lillie to be attacked by Nihilego and then tries to (for lack of a better phrase) Mind Rape her into forgetting the entire ordeal using Hypno. In other words, try to doom the world, he will stop you. Try to hurt his friends, he will straight up KICK YOUR ASS!!
In SM051, after Gladion and Lillie run off to Poni Island to find the key to opening Ultra Space, Ash, despite their insistence he not get involved, shortly makes a beeline to find them, and advances through the same trials they did offscreen quick enough to pull a Big Damn Heroes Electric Ball with Pikachu when the Totem Kommo-o's lair almost falls onto them.
In SM053, he performs a Diving Save at Lillie to protect her from Mother Beast Lusamine's attack.
As of SM067, Ash is the first character to have caught an Ultra Beast. Not accompanying or taking care of one, officially caught one.
Ash making his first Mythical catch as of SM112.
Ash has another strong showing against an Island Kahuna when he battles Olivia. Despite an experience disadvantage, Rowlet & Rockruff are able to defeat her Probopass & Lycanroc. He might have gone 2-0 if Rockruff hadn't KOed its own partner Rowlet by mistake.
While Ash fell short in his first battle with Nanu (thanks to his newly-evolved Lycanroc losing control vs. Krookodile), he more than made up for it in the rematch. Nanu made it a three-on-one gauntlet and Ash put his faith in Lycanroc. Ash learned from the previous battle and Lycanroc was able to defeat Krookodile this time around, then used its newly-learned Stone Edge to take out Sableye. Despite Nanu's inflammatory comments, Ash managed to compose himself...aided by another new move (Counter), Lycanroc went toe-to-toe with Alolan Persian. Z-Moves clashed and Lycanroc completed the sweep, earning Ash the Lycanium-Z.
Although Ash loses his first battles against both Hapu and Nanu, neither of these cases were official Grand Trials: Nanu's was a test to see if Ash was ready (and for Nanu to try and get out of it), and Hapu wasn't a Kahuna at the time. In his actual Grand Trials, the only instance of any of Ash's Pokemon fainting is Rowlet... who was taken out its own teammate, Rockruff, rather than by either of Olivia's Pokémon. This means that none of the Kahunas were able to knock out a single Pokémon during their Grand Trial against Ash.
In SM081, when a professional match with the Masked Royal's Incineroar ends up rigged by Viren and his goons, the Revengers, Torracat steps into the ring to defend Incineroar. Masked Royal's replying strategy? Form a tag-team match with Ash and Torracat against the Revengers. Ash even wears his own luchador attire for an extra awesome touch.
The Alola League. After more than twenty years and over a thousand episodes of the anime, Ash wins a league in one of the main regions, becoming Alola's very first Champion in the process. He's come a long way since he started. Heck, Ash himself can't believe that he won at first!
Crossing over with Heartwarming, after the episode aired, Veronica Taylor (Ash's original English voice actress for the first eight seasons of the dub) made a short in-character video to commemorate the occasion.
After becoming Champion, Ash does his exhibition match with Kukui and not only defeats him, but Tapu Koko who had just joined in to finally give Pikachu the rematch of a lifetime. Ash didn't just win the league; he obliterated it!
If this image is any indication, each of Ash's league losses has been referenced and turned around in a way in the Alola League.
Ash lost the Kanto League partially because his Squirtle was ruled unable to battle due to being put asleep by Sleep Powder. In Alola, Rowlet was thought to be knocked out in the battle against Hau, but was judged to be still able to battle when it turns out Rowlet was just napping.
Ash lost the Johto League with a Fire-type starter defeating his Fire-type starter, Harrison's Blaziken defeating Ash's Charizard. In Alola, Ash's Fire-type starter this time defeated another's Fire-type starter, Ash's Torracat defeating Kukui's Incineroar.
Ash lost the Hoenn League to an unevolved Pokemon wearing clothes, Tyson's Meowth. In Alola, Rowlet, an unevolved Pokemon, is seen wearing a Decidueye costume during the league.
Ash lost the Sinnoh League to Tobias, who used Darkrai (Mythical) and Latios (Legendary). In Alola, Ash had a Mythical Pokemon of his own (Melmetal) and a near-legendary Ultra Beast (Naganadel), and he defeated two legendaries (Silvally and Tapu Koko).
Ash lost the Unova League to Cameron's Lucario. In Alola, he defeated Kukui's Lucario.
Ash lost the Kalos League to his rival Alain in the finals, with Alain's Charizard winning the match with Blast Burn. In Alola, he defeated his rival Gladion in the finals, and his Torracat not only took Kukui's Incineroar's Blast Burn, but completely absorbed it.
Torracat's victory has two more factors in relation to the above. First, it staggers a bit before standing its ground, while Incineroar is the one that falls. This mirrors Alain's Charizard, who did the same thing when Greninja fainted. Second, Torracat evolves after the battle as opposed to during. To put it into perspective, Cameron relied on his Riolu evolving into Lucario in order to win and still lost to Virgil right afterward; Ash didn't have to rely on a similar Deus ex Machina during his fight.
For fans worried that Status Quo Is God is gonna run its course on Ash, Journeys episode 7 has Ash win a tournament with just Pikachu and Mimey — the latter seemingly done just to show Goh that any Pokemon can win a battle with a bit of effort and work to salvage Goh's battling spirit after a devastating loss to the same trainer. And given the reaction everyone, including the announcer, gives, it seems like Ash just used Pikachu through the entire tournament, leaving Mimey as a surprise in the end.
Ash making his first catch in Journeys: DRAGONITE!
Ash managing to help Goh in SS015 by coming up with a plan to lure out three Mankey shows the experience gap between the two as he gets results far quicker than Goh who was just aimlessly searching for them (albeit while using four fliers to cover a wide area).
In SS017, Ash captures the Gengar that was causing trouble six episodes earlier. And when Gengar is about to attack its former Jerkass trainer, Ash decides to take the high road and tell Gengar to stop attacking it (even if said trainer deserved being called out). It's also worth noting that Gengar has become Ash's first official Ghost-type Pokémon ever since he left Haunter with Sabrina and her family in the original series.
In SS021 after twelve years since its debut, Ash's aura powers become a plot point, leading him to an unhatched Riolu egg. In fact, his aura is so powerful that it helps Riolu (who was picking fights with anyone it saw) unleash a Vacuum Wave strong enough to topple an Onix.
At the end of SS022, when Goh says he's having Raboot Put on a Bus without even saying goodbye, Ash does not buy this shit at all and coldly asks Goh if he asked if Raboot was fine with this decision. Ash may be Goh's friend, but even he could tell that Goh was not being open with his feelings toward his partner.
In JN065, Ash defeats Iris, the reigning Unova Champion, only using Dragon types, which are supposed to be her type specialty! Not only does this mark the first time that Ash defeated an in-game Champion, but it also was Dracovish's proper battling debut! It really vindicates Ash as a top-tier trainer, considering some felt the Alola league wasn't a "proper" way for Ash to become a Champion. Even Iris says that he's not just a kid anymore.
In JN086, he uses Mega Evolution for the very first time, something that fans have been dying to see him use since Generation 6. And on his Lucario no less!
The whole lead-up to this moment is nothing short of epic. As Machamp and Lucario face off one last time with their teammates taken down, Ash wordlessly holds up his mega glove with a determined expression, with Lucario turn back and nodding with a smile. It's as if they are exchanging the words, "Now?" "Now."
Sure, it was offscreen and Played for Laughs, but in [JN105] he is able to beat former Hoenn Champion Wallace, gaining full respect from him.
JN109: Ash beats Raihan and is in the Masters Eight, a group which includes 6 (that’s right SIX) regional champions and Alain, quite possibly the best non-Elite 4 trainer in the anime. Ash will be battling in a tournament with trainers who may as well be called Pokemon Masters, and given that among the ranks of these trainers are well-known powerful trainers such as Cynthia and Alain; it's clear his toughest battles are about to come with Ash having never been more ready for them.
JN118: For anyone fearing that his victory in the Alola League and string of wins against everyone not named Leon were an overly-long fluke, which the anime has been known to do on multiple occasions, Ash assuages the concerns defeating Steven - ranked third at the time - in his first round of the Masters Tournament, proving once and for all that he belongs in the Masters Eight.
JN125: Ash defeats Cynthia in her first onscreen outright loss and advances to face Leon in the Finals. 15 years ago in Diamond and Pearl, he made a promise that he would be the one to defeat Cynthia, and now he has kept his promise.
For his defeats of two Champions in the Master Eight, the Team Rocket Trio dub Ash the Champion Killer.
Ash versus Leon. A four-part battle where Ash, per a Corocoro article about Leon's past battles, becomes the first trainer to ever defeat more than two of his Pokemon in a single battle. Regardless of the end result, Ash has become the person to most push Leon just by the end of the second part of the four-part battle.
And then Ash wins. That kid from Pallet Town we've been watching for so long? He's now officially the very best, like no one ever was.
Announcer:It's decided! We now have ourselves a new champion! From the Kanto region, born in Pallet Town, ASH KETCHUM!!
Note, the battle between the two is so fierce it starts to distort space itself.
The fact that in Japan they actually aired Ash winning on the big screens in one city.
After the episode aired in the real world, "HE DID IT" became one of the top trending on Twitter as everyone celebrated Ash's win.
Pikachu
How about the pilot episode? Pikachu crawls to its feet after being badly injured and rushes - illuminated only by periodic lightning flashes - to the defense of his (suicidal) trainer. After which he annihilates an entire flock of Spearow. With one attack. And how he does is even awesome. Pikachu is too tired to move on his own, and doesn't have the energy to stop one, let alone the entire flock coming at him and Ash. So what does he do? Jump into the path of a lightning bolt and use that energy to annihilate the flock in one AOE attack.
For those who are new or still wondering why Ash hasn't gotten a Thunderstone, the Vermillion Gym showdown should explain why (besides the fact that it's the most familiar critter...). What sealed it was Brock's suggestion that Pikachu learn the speed moves that Raichu missed out on. It was a way of saying "I don't have to be just like you to succeed." Without that experience, Pikachu would have stayed a one-trick Pokemon. Also counts for Fridge Brilliance: Raichu is undoubtedly stronger than Pikachu in terms of pure speed and strength, but Pikachu has more battle capabilities if kept in its earlier stage first, being able to learn more moves than Raichu and actually having more uses in battle come Gen 3 with the introduction of the Light Ball. This comes to a head in B/W where it learns Electro Ball, and then again in S/M where it learns Electroweb, a move that Pikachu can normally only learn through tutoring, mid-battle.
The fight against Sho's Raichu mid-way through D/P: even though he lost to an even more brutal opponent than Lt. Surge’s Raichu, with better versions of his attacks and Hyper Beam, Pikachu still manages to win in the rematch through superior mobility and reflexes to wear Raichu down. It all culminates in the finishing blow where Pikachu uses Raichu's Hyper Beam to jump into the air and spin into him like he's Sonic the Hedgehog! If Lt. Surge somehow didn't prove that Pikachu doesn't need to evolve, this fight sure did.
When the twerps found Team Rocket, seemingly drowned, after the St. Anne sank, they all seem genuinely sorry, and do their best to give the trio a proper burial at sea...until they scramble back on the raft, claiming they're not dead. Pikachu snaps its fingers and gives a very clear "Chu!" of disappointment.
Jessie: You just don't know when to give up, do you? James: I wouldn't be so sure, Jess... Pikachu: Pika... *gives the look with sparks flowing from its cheeks* Meowth: UH OH! I THINK HE'S MAD!!
In Haunter Vs Kadabra, stepping up to the Plate to Battle Sabrina's Kadabra which last time badly beat him. When he sees Ash seemingly given up and terrified after Haunter has disappeared he stands in between Kadabra and him and manages to hurt the Psychic Pokemon with a Thunderbolt.
In "Bye Bye Butterfree", Pikachu jumps onto the windshield of Team Rocket's helicopter that they were using in their plot to snag the Butterfree. Pikachu (complete with an adorable smile and "Ka!") begins to charge up his Thundershock. Cue Team Rocket shouting "IT'S GONNA SHOCK US!" in an high-pitched panicky tone of voice, which gradually gets faster before dissolving into hysterical screaming as Pikachu blows up the helicopter!
In "The Problem With Paras", after an uppity Charmeleon disobeys Ash's orders and starts attacking him, Pikachu gets ticked off and incapacitates it with one attack. Even after gaining an evolutionary level, Charmeleon's clearly no match for the little electric mouse's powers.
The Orange League battle between Ash and Drake. Both are down to the last Pokémon, Drake with his colossal Dragonite, and Ash with Pikachu. Keep in mind that the Dragonite's already beaten Charizard, Squirtle, and Tauros before now. The dude who wrote the episode even gave Dragonite eight attacks (ten in the original Japanese) to make it seem unstoppable. After a fight, throughout which Dragonite is clearly dominant, Pikachu manages to dodge Dragonite's Hyper Beam, perch itself on the giant's head, and call down Thunder to take it down, winning Ash his first championship. The mouse who KOs the dragon.
That time when Pikachu BLOWS UP A POKEMON CENTER. He might've been empowered by generated electricity (and it was Koffing releasing gas that caused the explosion itself) but it still counts.
Pikachu defeating all of Wattson's Pokemon with just one blow.
The Battle Frontier episode where Ash and friends visit an egg farm, specifically the scene where Pikachu learns Volt Tackle. Team Rocket has stolen a bunch of eggs in their giant egg-shaped mecha. Pikachu can't use Thunderbolt for fear of destroying the eggs, so Ash has Pikachu use Quick-Attack instead. That Quick-Attack unexpectedly morphs into Volt Tackle and Pikachu rips right through Team Rocket's mecha and wrecks them!
In Ash's four-on-four battle against Brandon, Pikachu defeats Regice!
During Ash and Paul's first match against each other, the significance of Pikachu's Iron Tail attack on Elekid during their intense face-off in the climax is often overlooked. Despite appearing exhausted at the end, Pikachu's Iron Tail was so powerful that it caused Elekid and Pikachu to faint almost simultaneously, resulting in a draw and a thrilling outcome.
In his rematch with Roark, Pikachu takes a nasty hit from an Onix and gets buried under a pile of rocks. The Onix proceeds to set up Stealth Rock while it has a second. Pikachu then proceeds to, over the course of about five seconds, blast the rocks off himself and destroy the Stealth Rock and then charge right through its counterattack to Iron Tail it in the throat and land on the other side while it topples behind him.
Managing to tie with Tobias's Latios in the Sinnoh League. Latios is a legendary with a type advantage over Pikachu, who had just taken out Swellow and Sceptile without either getting a hit in. Even with a type disadvantage, Pikachu's tough enough to match legends.
The Electabuzz line has served as The Rival for Pikachu throughout the series. He had not beaten any member of its line without teaming up on it. Against Volkner's Electivire, it wins, despite not being able to use any of its Electric moves (due to Motor Drive). It does so by beating Electivire down with Iron Tail.
Pikachu in BW050. He's trapped, far from his Trainer, and Axew (who's essentially a kid) is panicking. Pikachu keeps his cool, starts letting out other Pokémon from Ash and his companions' teams, and rallies them like a general to escape. Little guy could probably make a decent trainer in his own right.
For anyone who thought Pikachu had suffered Badass Decay in early Best Wishes (thanks to several unfortunate losses), you need only see the Gym Battles against Burgh, Elesa, Skyla, and Roxie (especially Elesa) to realise that this isn't the case. At all.
During the Operation Tempest arc:
Breaking out of a cage (previously shown to withstand the attacks of even strong legendary Pokemon) just by hitting it repeatedly with Iron Tail.
Saving Dragonite from Therian Forme Thundurus.
The ungodly huge Electro Ball he produces from absorbing Thundurus's electricity, which completely pulverizes the platform Meloetta is imprisoned on. Here's the scene in its all glory.
An underrated moment is Pikachu's fight with Cameron's freshly-evolved Lucario. Despite being at a clear disadvantage due to Lucario's steel typing and superior strength, Pikachu still gives Lucario a fight to remember. Even Quick Attackmanages to do some damage! Granted, Pikachu still lost due to Lucario's overall greater battle prowess, but Cameron still had to give it his all to even claim a victory. And keep in mind, this is when Ash was at his lowest point in the series, development-wise.
Resisting the effects Colress's machine in the climax of the Team Plasma arc, and shocking Rehsiram into doing the same, leading to the eventual destruction of the machine.
Pikachu vs. Grant's Tyrunt. Tyrunt is much more powerful than Pikachu, but Pikachu managed to play Tennis Boss with it, reflecting all of the Rock Tomb back at it and making it "bite" out of one of the rocks, trapping it for Pikachu's Iron Tail to hit.
Pikachu Vs. Mega Lucario, which took up more than a third of the episode and definitely did not disappoint. Pikachu starts out the battle with a column of rage/determination fueled electricity, not even as an attack, but to show how Badass it was. Then it counters every hit of Lucario's with an equal one of its own, the highlight of which was Iron Tail Vs. Bone Rush where Pikachu (while in the air) pushes Lucario down with his Iron tail while Lucario blocks with his Bone Rush. And to cap it off we have Pikachu's final attack, which is basically Megavolt. Just look at Lucario's face right before he gets hit. And this is a MEGA Lucario belonging to a GYM LEADER.
Pikachu trying to rescue Ash and company's Pokemon in A Frenzied Factory Fiasco! is a moment at its best. The episode involves him:
Freeing himself from the glass cage, finally getting round the electric resistant trick by just knocking the cage to the ground with his weight.
Avoiding being returned to his Pokeball (and at one point tricking Team Rocket into thinking they caught him by hiding in an air duct).
Kicking Meowth in the face.
Using a Luxury Ball on Meowth to escape.
Dodging Meowth's sneak attack with his Pokeball mid air and defeating him with Iron Tail to get back the briefcase of stolen Pokemon. This one gets special mention, since it resembles a Single-Stroke Battle.
On a side note, Ash called zero attacks in any of these. Pikachu worked on his own initiative to evade and take down Team Rocket, especially since Wobuffet, Inkay and even Meowth were putting up a much better fight against him than usual.
All but one attempt to force Pikachu into a Pokeball have failed (the one exception being Mewtwo via his cloning device). Even Meowth, a wild Pokemon was successfully warped into a Pokeball more times than Pikachu.
In the infamous Electric Soldier Porygon episode, Pikachu manages to save both Ash, Brock, Misty, and the entire Team Rocket trio by blowing up vaccine missiles aimed directly at them. (And causing seizures in Japanese school children as a result.)
Defeating Sawyer's Clauncher was expected. Defeating his Aegislash on the other hand....and Pikachu did so brilliantly by blocking up the sheath so it couldn't defend.
In the Kalos League finals, Pikachu pulled a great feat in defeating both Alain's Metagross and Tyranitar (both are fully evolved pseudo-legendaries by the way) BY HIMSELF! Such is the power of Ash's first pokemon we've been doubting all these years. In fact, Pikachu completely curb-stomped Tyranitar, in the whole fight Pikachu dominated and Tyranitar didn't get one single good hit in. What makes it even better is that Alain's reaction to seeing Pikachu beat Metagross is to immediately send out his Charizard next instead of Bisharp, with the implications that he's trying to take down Pikachu as soon as possible before it does any more long-term damage to his team, while at the same time honoring his strength with the chance to face his ace. And despite the fight with Metagross clearly having taken its toll on Pikachu, he still has enough power to zap Charizard and bring it down to its knees.
Sending Hala's Hariyama flying using Breakneck Blitz.
In the rematch against Tapu Koko, he actually manages to land a hit on Tapu Koko with Iron Tail, and briefly send it flying with Gigavolt Havoc. Sure Tapu Koko still technically wins, but give the mouse a massive A for effort. Also note that it was Tapu Koko who called for the battle, having taken interest in Pikachu's power after he and Ash create an enormous Z-powered energy blast. It even dismisses Rowlet and Rockruff to select a one on one with Pikachu. A legendary considers Ash's Pikachu its Worthy Opponent.
During Ash's foray into Ultra Space, his Electrium Z gets a power boost. To what level? Oh, nothing special, it just transforms into a Pikashunium Z. And the resulting attack is a true thing of beauty, with Pikachu letting out a massiveBattle Cry and having thunderbolts in blue, green, purple and red.
Ash: Much bigger than a Thunderbolt, 10,000,000 Volt Thunderbolt! Yeah! This is much, much bigger! At Super-Full Power! 10,000,000 Volt Thunderbolt, now!
In SM067, after suffering several beatdowns from Team Rocket's Mimikyu in the past, Pikachu in this instance very handily dodges all its offense and is only robbed a proper defeat by Bewear.
Anytime Pikachu gets distracted or incensed enough to fry the entire vicinity around him. Both the "Pikachu and the Music Squad" short and "Alola, Kanto!", while Played for Laughs, have him let out a fully charged Thunderbolt that takes down pretty much every single Pokemon in the main cast (along with the trainers in the latter).
In SM076, Pikachu once again battles Mimikyu and while he's originally at a disadvantage. Pikachu manages to turn the tide by unintentionally using a newly-learned Electroweb to block a Z-Move and then using Electroweb again to trap Mimikyu as Ash's Electrium Z once again becomes a Pikashunium Z, allowing Pikachu to use 10,000,000 Volt Thunderbolt to beat Mimikyu.
Pikachu is used in the Poni Grand Trial against Hapu and her Mudsdale, who not only is a Ground-type, but has Stamina as an Ability, which leaves him in a huge disadvantage both type-wise and power-wise, as Stamina increases Mudsdale's defense after taking damage. However, he manages to hold on despite a super-effective Tectonic Rage that flung him in the air, using Electroweb to soften his landing and land in the water, luring Mudsdale to attack a pillar with Bulldoze and causing it to get wet with the seawater, which creates the effect of the move Soak, making it a Water type and thus weak to an Electroweb. He then wins with Gigavolt Havoc.
Being responsible for the first onscreen defeat of Guzma's Golisopodnote other than a victory by Kukui's Braviary shown in a flashback, especially when Pikachu gets his first solid hit in by knocking Golisopod's legs from under it and following up with a point-blank Thunderbolt. While it's revealed that Guzma's undefeated streak is due to Guzma only picking fights that he knows he can win, it's also made clear that Golisopod is extremely powerful and it manages to push Pikachu to his limit.
Gladion's Silvally is fast enough to dodge and counter Pikachu even when the latter uses Quick Attack, so what does Ash have Pikachu do? Launch Electroweb and Quick Attack in rapid succession, knowing that Silvally will dodge them, then use Electroweb as a makeshift trampoline to land a high-powered Iron Tail! Combined with the damage already dealt by Melmetal earlier in the match, it's enough to take Silvally out. Even more awesome is that Silvally is a Legendary. Pikachu just took out his third Legendary Pokemon throughout his entire journey!
During his battle against Gladion's Zoroark, Pikachu is seemingly cornered by Never-Ending Nightmare, but manages to invoke Taking You with Me with Breakneck Blitz, leaving the final batchup of Lycanroc vs Lycanroc.
The final battle with Professor Kukui has him defeating Tapu Koko with a 10,000,000 Volt Thunderbolt, making Tapu Koko the fourth legendary he has defeated. And he not only defeated Tapu Koko, he straight up overpowered the Island Guardian's own signature Z-move!
Despite his huge victory at the end of Sun and Moon, Pikachu once again subverts the usual next-series-nerf in Journeys. In his first face off against Team Rocket, they show off their newly gained access to the organization's reserves. Despite them pulling out a Gyarados and Tyranitar, Pikachu, still manages to overpower a dual Hyper Beam from the both of them and blast them off.
In Ash's first official World Championship battle in SS018:
Pikachu goes up against Visquez's Raichu. In a humongous Call-Back to Pikachu's battle against Lt. Surge's Raichu, Pikachu tanks a Volt Tackle via planting his (Iron) Tail to the ground! And when sent flying into the air, Ash has Pikachu using Iron Tail again to spin round and round before rebounding from a wall.
Against Visquez's Electrode, who uses its electricity to levitate chunks of rock and unleash a barrage of attacks like a giant pinball, Pikachu stops it in its tracks with Iron Tail before reversing its direction. And when Electrode decides to use Aftermath, Pikachu uses Electroweb to protect itself!
In Ash's first round in the Master class tournament fight against Steven in SS118:
Pikachu made short work of Cradily, using Ash's ever ingenious battle methods with Electro Web to trap it's tentacles and leaving it open for an effective Iron Tail.
Pikachu proves to be a Metagross killer indeed. Steven's Mega Metagross proved to be too fast for Pikachu to reliably hit and taking a massive beating to boot, Pikachu grits through the pain. Ash and Pikachu pull out their secret weapon, their z-ring and crystal. With the power that defeated Tapu Koko, Pikachu overpowered Mega Metagross' attack and hit it with a barrage of 10,000,000 Volt Thunderbolt, leaving it wide open for a devastating Iron Tail to defeat him and ending the fight.
In Ash's semifinals match against Cynthia, despite Goh saying he should swap out Pikachu because he wouldn't stand a chance against Cynthia's Gastrodon, he keeps using him instead and defeats it very quickly using Iron Tail to send its Stone Edge back at it then finishing it off with Quick Attack, giving Ash his first knockout against Cynthia after both Dragonite and Gengar had fallen. Pikachu would later follow up by defeating the Pokemon who Cynthia had used to beat Dragonite and Gengar, Spiritomb, albeit with Pikachu being caught by Destiny Bond in the process, beyond that Pikachu hadn't even taken any real serious hits against either Pokémon (part of what made the Destiny Bond twist so shocking) in every other Full battle while Pikachu often does defeat two Pokémon, it's never without serious effort and taking a lot of damage, here Pikachu gives what is possibly his best ever showing and could have easily gone another few rounds, which is beyond impressive considering who he was up against.
Heck the simple fact that Cynthia's entire opening strategy was dedicated solely to taking down Pikachu, and ended up using four Pokémon to do so says a lot about what she thinks that little mouse could do to the rest of her team, or even her ace Garchomp.
JN132: This is Pikachu's crowning moment episode, literally. Despite facing Leon's Cinderace and the undefeated Charizard alone, Pikachu manages to prevail and beat BOTH of them, giving Ash the victory and the title of Monarch. No amount of words can do justice to the sheer feats Pikachu pulled to make this happen. And the last attack Ash gives to Pikachu contains the original, in both the Japanese and English versions, theme song for a grand Theme Song Power Up!
The finale of the battle cannot be understated just for how amazing it is. After an incredibly fierce battle against Charizard, Pikachu ends up being nailed with a MASSIVE Fire Blast, and despite all his efforts to stay conscious to continue the fight, he collapses and blacks out, seemingly losing the battle... As he's suddenly met with visions of all of Ash's Pokémon over the years (Even including temporary and former friends) cheering him on to keep going along with Ash himself, as Pikachu manages to get back up with an incredible display of lightning unlike any before seen in the series - a display which, thanks to the sheer volume of golden lightning forming a bona-fide Battle Aura, makes it look like Pikachu has gone Super Saiyan. It is just as awesome as it sounds.
The final attack that decides it all? An improvised Thunderbolt (Which almost resembles a Volt Tackle in this case) and Fire Blast (which takes the form of an improvised Flare Blitz) in a head-to-head melee clash that Pikachu manages to overpower Charizard in, winning the battle and Ash the title of World Champion.
Ash: Pikachu! [flips his hat] We're gonna put everything we got into this attack! [Pikachu charges up his electric power] Leon: Charizard! [tosses his hat in the air] Let's have a champion time! [Charizard charges his fire power] Ash:Thunderbolt,let's GOOO!! [Pikachu unleashes a full powered Thunderbolt] Leon:Fire Blast,NOW!! [Charizard unleashes a full powered Fire Blast] Ash/Leon:LET'S GO!!! [Pikachu and Charizard charge at each other into a powerful head-to-head melee clash]
.
