In Episode 9 of The Legend of Zelda: A Link to the Past, Arin is able to take out the Helmasaur King without a scratch, having entered the boss room with only one heart. Made even better by Jon's nervousness during the fight and genuine amazement at Arin's skills.
Defeating Wily within a couple of tries in Mega Man 7, a notoriously difficult boss that the developers even apologized for. Notably, they didn't even use Wily's actual weakness.
Jon, self described as being ignorant of the rules of Pokémon, actually managing to very nearly defeat Ego in Pokémon Stadium, who is much better versed in the rules.
It's also a form of Damn You, Muscle Memory, as many of the rules of Pokemon weren't really established until the 3rd gen, which meant that pure luck as Arin had was a viable strategy back then.
For a while after the channel started, many of the fans believed that Jon was worse at video games than Arin. Cue the second Game Grumps VS when they play Super Smash Brothers Brawl with new controllers- Jon shows that he is actually consistently better than Arin at that game.
Jon tearing through Super Mario Land with little difficulty. He accidentally reset the game on the last world, though.
Arin mentions doing something even more phenomenal with the original Super Mario Bros After approaching a setup with the full game active for anyone to play, he decides to goof around and act like a stereotypical new-age gamer, calling it too easy. He proceeds to speedrun the game all the way to 8-4, the final level in the game, without getting hit. When he finally did die, he tossed the controller down, insulted the game and stormed off to complete the image. In short, he nearly did a perfect speedrun of Super Mario Bros just to fuck with people's heads.
Jon takes down the oft maligned Radical Train mach speed section in only TWO tries.
Sonic 2006, part 35: Jon manages to pull off getting through Kingdom Valley, including beating the Mach Speed Zone on their last life. The fact that this finally lets them progress through the rest of the game after being stuck in an incredibly mundane rut of Sonic's story makes it all the more satisfying.
Jon beating Silver (Arin almostbeat him) in Shadow's story after they spent an entire part and a half on it. Especially because he was an even moreunbearable boss than when they first fought him as Sonic.
Episode 85 of Sonic 06 is called "Catharsis" for a reason. When Arin gets to the boss battle versus Sonic in the Silver campaign he gets their much needed revenge by proceeding to deliver an absolutely epic Curb-Stomp Battle against Sonic, all while Laughing Mad and having a a beautiful A God Am I moment.
Arin:I WIN! MY WIN! ARIN WINS! SILVER WINS! SONIC WINS!
They've survived over 100 episodes of playing Sonic 2006 while clearly disliking it, though they of course like playing it with each other so Power of Friendship can overcome the impossible.
Arin Game Overs in one section in Wild Guns, leaving Jon (who has one life and no bombs) in an arena so clogged with enemies and gunfire that he has to constantly jump just to stay alive. Not only does he manage to clear the stage, but he beats the mid-boss afterwards. Unfortunately, he eventually dies to the stage boss, but he gives it a hell of a fight beforehand and nearly wins.
The Chivalry Medieval Warfare episode comes to a climax with Jon and Arin tied 2 for 2, the entire game coming down to one final round. After Jon requests some "more ABBA MIDIs", the battle begins to the tones of a low-quality version of Gimme Gimme Gimme. Jon clinches the victory spectacularly in a fashion that astounds even Arin; by jumping onto his blade, parrying his next attack and countering with a heavy blow against Arin's neck.
Dude, you fuckin' jumped! You jumped onto my blade like Dark Link!
After several failed attempts, he does it again... and then proceeds to stunlock The Grim Reaper with Holy Water and kill him without taking any damage either. In fact, he manages to stun him before he can even spawn his scythes.
And he does this again with Dracula's second form.
In Mario Party 2 Revengeance Jon ends the game 7 stars, which is impressive considering that the game only lasted 20 turns. In other words, an average of a star every 3 turns.
Arin managing to win against Jon in Space Jam with a team of players who all have terrible stats compared to Jon's team. By one point. It's even more ironic when those players with terrible stats were the Monstars, who absorbed the Basketball talents of some of the most talented Basketball players out there... Oh, and Shawn Bradley.
Their playthrough of Cookies and Cream has them actually working together and reading the hints to figure out the puzzles.
After spending the entirety of the Puyo Pop Fever! episode playing horribly, Arin manages to launch a massive combo string at the last moment, winning the final match.
Twice during Shatterhand Arin gets the super suit just in the nick of time to fight the ninja boss, a boss he dreads, and beat him just before the power up disappears.
In Danny's second outing as Not So Grump, the Grumps played Super Mario Bros. 2 Danny managed to completely steamroll through it. It's especially prevalent in World 4-2, where he managed to completely avoid damage in a section where enemies were practically coming every second from every height.
Danny fighting Wart in Super Mario Bros. 2 is awesome. He gets hit and cuts it close, but he still manages to dodge some truly insane bursts from Wart - at one point, Arin jokes that he will NOT be satisfied unless the final hit is done with the "happy tomato" that pops up rarer than the other vegetables. Guess how Danny wins?
Arin: This could not have ended more perfectly.
The utterly epic pet theory at the beginning of episode 3 of Mike Tyson's Punch Out that, since "Macho Man" Randy Savage died the same day as a rapture scare, the reason that the apocalypse didn't happen was because Randy Savage beat up the horsemen of the apocalypse at the cost of his own life.
WHAT'S UP, PESTILENCE!? WHY DON'T YA SLIP INTO A SLIM JIM!?
On Danny's final attempt at beating Mike Tyson in Punch Out he punches Tyson just as he's blinking and knocks him down, to both Grumps' great surprise since they had no clue about that trick.
Danny beating the Karate Kid in one part. He practically blazed through a few of the levels and the bonus stages without even blinking. A bit more awesome when you recall that this is the first One-Off Danny did. Compared to the first one Jon did (Battletoads) this might become one of his more significant Establishing Character Milestones.
Arin defeats Danny's Big Zam in ''Gundam: Battle Assault 2 by getting behind it and pummeling it. Also knowing how to use the Big Zam's main cannon when it's Big Zam vs. Big Zam.
Part 7 of Kirby's Epic Yarn when Arin and Danny keep on messing up the parasaurolophus segment, because they can't seem to coordinate getting on its crest at the same time. Nearing the end, after Danny says they can't end the episode without crossing the river, Arin falls in once more while Danny is still on the parasaurolophus, and out of sheer frustration he manages to plow through the water by mashing the 2 button really fast (catching up and getting back on the dino). The fact that he sounds like he's powering up helps.
Arin's defeat of Phantamanta in a single try during Part 19 of their Super Mario Sunshine play through. Even after having been brought down to one health point during the fight he manages to get it back and take down the boss.
It should be noted that at the time, this was officially the longest play through that the show had completed (which has since been surpassed by Wind Waker).
Arin and Danny beating Contra in just one episode.
Arin clearing World 6-5 on Super Mario Bros. 3 on his first try after seeing Danny run out of time on his first attempt. This came after a brutal stretch on 6-Fortress 1 and 6-4 (where Arin decided to use a P-Wing after they had enough of it otherwise).
Followed shortly after by him beating the final castle and Bowser. (he used a P-wing to speed through the castle, and Arin told him the trick to the fight, but still)
Danny's story of overcoming depression ends the story and the depression by going to France, looking at a beautiful lake in the village he was staying in and throwing his medication into it when he realized he needed it no longer.
Double awesome for responding to the feedback a few days later - and saying that he got away with something stupid and that others should not do the same and instead contact their doctor when they feel they no longer need medicine. As awesome as his story is, it is a dangerous act, and he got lucky and acknowledges it, and doesn't wish for anyone else to make a mistake.
Arin beating Outrageous, possibly the hardest level in Super Mario World, on his second try.
And before that, managing to make it to the secret exit in Star World 5 even though he'd forgotten to activate the blue switch first.
Arin: YEAH-HEH-HEH!!! WOO!!!
Danny: SUCK EVERY DICK IN THE WORLD!!!
Danny barreling through the castle and the final boss fight in one go, only taking damage at one point before defeating Bowser without taking any damage at all. This after Arin teased him about not being a good player!
In the Super Metroid run the lesser boss Crocomire gives Arin a really tough time. Even without Arin knowing about the charge shot it is very satisfying when Arin returns the favor in the following episode.
Arin taking down Ridley in only his second attempt surely counts as well.
Danny singing all the requests at Magfest 2014 and the duet with Arin for the intro.
While playing Ribbit King, or Frolf, the fourth episode has Arin winning during a game. Arin has his frog in a hole with a big lead over Danny. Danny gambles on taking an extra round to gather points and when it comes to getting his frog in the hole there is a long chain of events that racks up many points and then the frog goes in. Danny gains so many points that he... still loses by ten but still that was an impressive catch up.
In Part 12 of Katamari Damacy Danny tells Barry to end the episode prematurely. Barry's response is nothing short of impressive.
Danny taking up the mantle of Not-So Grump, thus saving the show, knowing full well that thousands of irrational fans were going to hate his guts. It can be summed up in this line from Wind Waker part 42:
Danny gets a small one in the third episode of Punch Out on Wii. Instead of learning how to duck King Hippo's new move, he instead successfully counters the move several times. The rest of the episode is against Piston Hondo and almost got TKO'd in the first round. Danny is gradually able to grind against Piston's style, turning a 180 and having the third round be one punch and T King Hondo.
Then, in the fourth episode, Dan is knocked out by Great Tiger, seemingly defeated. Then Little Mac's Heroic Second Wind activates, allowing Dan to defeat him. Much later (before the final Mr. Sandman fight, see below) Danny says he did it accidentally, and that he didn't even know about that trick until then.
Episode 9. Not only does Danny TKO Bald Bull on his first try, but he successfully counters his charge both times.
The fact that he had managed to make it to Bald Bull without realizing he could duck
In Part 10 of Wii Punch-Out, Danny finally dodges the Super Macho Man Punch which had already flattened him several times already.
In Part 11, after doing relatively well against Mr. Sandman, he gets knocked out a third time. Then, just like the Great Tiger fight, Little Mac activates his Heroic Second Wind, allowing Danny to win in the third round. Cue the applause from the fans.
By Part 11, Danny has finally learned the tricks of the game and used them to beat Mr. Sandman. So, how does Danny react to Title Defense? He acknowledges that he needs to get better, and that they're putting the series on a small haitus so that he can improve before moving on. It shows that the grumps really do care about how they play the game, making this an awesome decision in a heartwarming way because they're doing it for the lovlies.
During Date Grumps with Suzy, Arin completes the waterfall log sequence in The Lion King where Suzy could not.
Part 36 of Pokémon FireRed is entirely animated, due to game footage being lost. And the first half of 37 as well. Both videos got many more viewers than contemporary playthrough episodes because of it, since things were Off the Rails, unpredictable, and interesting to watch.
Linzbot had a mere four days to do it too. She even takes time to make Part 37 segue from animation to normal pixelated gameplay flawlessly.
The end of Part 22 of Shadow of the Colossus: Danny gets knocked off Phalanx for the second time, and they do the usual wrap-up lines. Then we cut to him back on Phalanx and announcing we'll see him win right now.
On his third trip up Malus' arms, Danny manages to sequence break straight to his head, and never gets thrown off from then on.
"This is for AGRO!"
Danny's completely improvised song at the beginning of Part 27. Doubles as a Funny Moment.
I've walked many miles / And lived through these trials
Arin proves to have a remarkable memory for the various secrets of Super Mario Bros., even using two warp zones to get all the way to the final level by the end of the first video.
He manages a remarkable run through World 8-3 without any power-ups, past a bunch of Hammer Brothers, despite the game's controls being rather more slippery than they're used to.
Danny's run straight through 8-3 while on his last life, and Arin already out. It includes barely clearing a piranha plant.
After Arin beats the game, he speedruns all the way to 8-3 on one life.
The final round of Kirby's Dream Course. After Arin challenged Danny to winner take all round, Dan proceeds to take a huge lead when Arin spends the first half trying to get off the initial ledge. After he manages to get off, however, he uses an amazing trick shot to steal two of Danny's stars, putting them in a race to the hole to determine the winner. Danny's put his Kirby on same ledge of the hole, knowing that Arin can't sink his in the next shot. However, Danny's Kirby falls asleep on the next turn, allowing Arin to make one more shot from the bottom ledge, which he proceeds to sink.
The Grumps return to Dead or Alive to try once more to woo Helena, having gotten a lot of research and advice from the Lovelies. Offhandedly, they decide to ask her to partner up before they can put any of the info to use, and at random, she accepts the offer within the first minutes of the episode!
Dan winning all four floor tile Mexican Standoffs in the eponymous episode.
After several failed attempts at Red-Hot Run, Arin spots the gold tanooki suit in the beginning and completely smokes it, constantly leaving Dan in the dust.
Arin grabbing the final star of a ten star course at literally the last possible moment, after twice failing by that moment.
Dan somehow getting past three tightly packed Big Boos in Part 50.
On August 9th, 2014, there were no new videos: technical issues with Youtube prevented Barry from uploading. The awesome part is that, as Barry pointed out on the official Game Grumps twitter account, they had never missed a day before.
The situation: All five Grumps get into a challenge where they have to pour buckets of freezing ice water over their heads. At night. They do so, and they all react with the usual reaction one would have. Except for Ross, who stood perfectly still throughout the entire video, even when everyone left.
The last-minute save in episode 5 of Trauma Center Second Opinion.
In episode 9 they hopelessly screw up the operation the first time, but on the second try they work together like a machine and earn their first A rank.
In episode 18 they save Tyler's sister without even using the Healing Touch.
Arin somehow getting a perfect score in the bungee jumping event of Go Vacation, (00.00 feet from the ground!)
In Mega Man 6, defeating Centaur Man with a single health bar remaining. And somehow made even more badass by them not even noticing.
Arin scoring a single point in Nimble Thimble from Minute to Win It at the very last instant, after they both spent the whole minute struggling to figure out how the game worked.