How about in the manga where Manta, in order to get a sword for Yoh, beats up Ryu and Co. with his dictionary!!! In the anime, this is changed to RYU and Co. saving Manta from the gang he was trying to get a sword from. They were both different, but still awesome nonetheless.
Yoh gets one afterwards when Anna sends the spirit of Shaolin, Lee-Pai Long's master into Yoh. Shaolin-in-Yoh proceeds to Curb-Stomp Lee, from blocking all of his attacks, to striking him down with a Kamehame Hadoken. Shaolin-in-Yoh ends the fight with a charged double fist strike.
Yoh has quite a few moments, but one that stands out is during his fight with Horohoro, where he, acting on muscle memory, performs the Shock Wave Buddha Giri, Amidamaru's signature attack, mowing down a field of icicles created by Horohoro. What really makes this an awesome moment for Yoh is that it's the first "real" fight where it's Yoh pulling off all the awesome attacks, with Amidamaru forming the Over Soul instead of possessing him and doing the work.
Not to mention Yoh and Horohoro's final attack during the fight. Furyoku-pumped-up-Amidamaru Slash vs. Extreme Avalanche.
Yoh and Tao Ren's third fight for them to enter in the Shaman Tournament. All of it. The battle was SO EPIC, the dub episode had to spoil the ending. The name of that episode; One, Two, Three Draw.
"Wooden Sword" Ryu revealing a new form of his Tokagero Over Soul and just utterly wrecking Boris Tepes Dracula with it. Immediately before doing that, Boris tries to gank Ryu while he doesn't have enough time to turn around or draw his sword. Ryu's response is to backhand Boris in the face and tell the punk that he's a street fighter first, swordsman second.
The anime expanded on this fight, the only difference from above is that Ryu and Horohoro comboed him. The best part of the fight came with the group's Batman Gambit. Boris' spirit partner has possessed Lyserg (though he fights off long enough to ask Yoh to finish him off). Meanwhile, his bat spirits have a bunch of sharp spikes above Ren, Trey, and Ryu, and if any of them make a move, the spikes will fall on them. So how do they get out of this one? Yoh lets Lyserg bite him, but it turns out that he and Amidamaru performed Spirit Unity "BEFORE" the fight and Amidamaru captures Boris' spirit partner freeing Lyserg as well. Enraged, Boris has the bats drop the spikes, only for Ryu and Trey to grab and freeze the spikes, leaving Ren to finish of Boris with a Rapid Temp Assault.
During the "Rescue Ren from his Father" arc, we have:
When the gang is facing down Ren's father, Yuan Tao, Ren finally realizes the secret behind his father's enormous size, inhuman power, and apparent immortality. The man that he's known all his life is actually an Over Soul. So he makes several composure-shattering proclamations and observations to him, and then just stands there, Over Soul deactivated, as his raging father makes another swipe at him. The Over Soul just passes through him, proof that he's rattled his father to the point that he can't even focus on keeping his Over Soul up anymore. Then after Yoh and the gang manage to hurt him. Ren goes in full force, laying an ass whopping, and when his father uses his trump card, the Tao Family Dragon, Ren Over Souls Bason to max and puts a Golden Sledgehammer in his face.
He gets another one during his first fight as an X-Law against Team Niles for the second round of the tournament (In the anime, this happens a few episodes before the tournament). Using only Chloe, he increased his skills to take on all three members and crushing Anahol's arms. He would have killed them if Yoh didn't ask him to stop. Then Lady Jeanne comes in, and kills all three members in less than two minutes.
During a side-story focusing on him, Horohoro, faced with the dilemma of the life of a human-hating grizzly bear, loved by the park ranger who saved his life, being threatened (by law; if he attacks humans, he'll be put down), he decks himself out in full Ainu shaman garb, marches right up to the grizzly in question, and proceeds to sit down and offer him some sake. He proceeds to try and discuss the situation with the bear, despite getting nearly mauled several times (by the several hundred pound grizzly bear). Finally, he gets through to the poor creature; but just as it looks like the whole story will end happily, a trio of poachers shoot the bear dead on the spot, and then try to run when they see the park ranger. Horohoro, a believer in the laws of nature, demands that the hunters at least take their kill with them when they leave; when he finds out from their responses that they killed the bear for sport, and not for food, he goes apeshit. The hunters panic and shoot him, only to find that he's just manifested a shell of ice around his body, stopping the bullets cold. Seeing this, they panic again and shoot at him, only for him to stop them with a wall of ice. And finally, he manifests a completely new Over Soul, which can only be described as a Laser Blade made of pure cold. With a mighty swing, he fells several trees behind the poachers, and immediately locks them right there in the air with a huge mound of ice; but he doesn't touch the poachers. His last words to them are: "I won't kill them. If I did, I'd be as worthless as they are."
Horohoro's second moment was him defeating Brocken. To summarize, Bill and Brocken were killing off defeated Shaman King tournament participants, and the Ice Men were next. Horohoro decides to protect them since he's mad that Ren died. He's almost killed when his dad arrives to knock out Bill and remind his son of "Survival Of The Fittest". So Horohoro comes up with a unique plan. He uses his brains, and uses the Ice Men's spirits to lead Brocken into a trap and encased him in a block of ice. With him out of the fight, Horohoro lies in victory, but Bill has survived to finish him off. Who saves him? Lyserg. With his new angel, Zeruel.
Horohoro gets another one when his team "The Ren" are completely demolished by The Gandhara, a team with Godlike Spirits. Horohoro begins to flashback to Pascal Avaf's training and he and Kororo awaken the Nipopo Gauntlets, a new Over Soul, that forms giant gauntlets of ice that cover his entire arms. Cue Curb-Stomp Battle, and Horohoro wins the round for his team. Most importantly, however is that during the fight, Lady Sati, declares that Horohoro will be the Fifth Elemental Warrior, which means he will be getting the one of the Five Elemental Spirits (the Spirit of Rain specifically). If you need help imagining what that means, just think of Hao's Spirit of Fire.
Opacho: "Horohoro scares me."
Anna using one of Hao's spells and a 1080 bead rosary to force two of Hao's demon servants into submission in seconds. Of note is the fact that the book she found the spell in released said (murderous) demons the second it was unsealed.
Also, Anna walking up to Hao and slapping him in the face. For badmouthing Yoh and the gang. What makes this even better is when he catches her hand and tries to flirt with her ("You truly are worthy to be the wife of the Shaman King..."), Anna flinches a bit and then she slaps him with her other hand.
The Lily Five's first match of the tournament is against Zeke's team. The Lily Five are to stubborn to bow out and so Yoh challenges them to fight him before he'll allow them to face Zeke. Then the most amazing thing happens, they actually manage to beat him by pulling their act together. Sadly they all ran out of furyoku and are therefore unable to fight Zeke, so they drop out anyway. Still, it was pretty cool seeing the girls improve so much and hold their ground. That and they became known in-universe as "The Five Girls That Stood Up Zeke". And Zeke was pissed.
In the manga when Chocolove comes back from the dead to face-off against the Golem, he tells the bound ghost that is piloting it: "I killed you on Christmas three years ago. But so what?" What really makes that Badass Boast work is the fact that he was previously shown feeling guilty about it. His 'so what' does not mean he doesn't care, but that he isn't going to let his guilt rule him any more. BAD. ASS.
Marco vs. Anahol. Let's just say that there's a reason why Michael and Marco are the de-facto leaders when Jeanne's not around.
Yoh borrowing his father's spirits to fight against Team X-II.
Yoh and the Elemental Warriors return from Hell. Special points go to Yoh for unleashing his new Over Soul, Spirit of Sword: White Swan on the same person who beat Hao 500 years ago; Yohken Asakura and Faust reviving him to do the same to Big Bill, Zhang-Ching and Turbine, and Team Ren coming back to stop Hana-Gumi from killing Gandhara.
Before that, we have Anna vs. a-pissed-off-Hao. Did we mention that Anna has over 600,000 furyoku, half of Hao's 1200000 level. Yeah. Its was a fun fight.
The reason why Hao was pissed. Team X-II destroyed his base and almost KILLED HIM with a Satellite LASER BEAM.
The tournament battles in the anime were also impressive and showed character development for at least half of the main characters.
Ren defeated his older cousin and twin cousins BY HIMSELF, ensuring that he is the heir to the Tao throne after facing punishment from all three for their attacks.
Ryu destroying Haloune's genie using sheer will and O.S. Yamatao no Orochi, and saving Haloune's and Anith's relationship.
Horohoro using The Power of Love from Pilika's heart to beat Team Doom's Dragon Over Soul.
Joco overcoming the darkness in his heart in the most funniest way ever.
Four words: MORTY BECOMES A SHAMAN. And Mosuke returns.
Yoh and Co. vs Hao/Zeke and followers in the last eight episodes of the anime.
During that, we have Yoh teaching Len how to properly use Giant Spirit Control to channel it into a stronger form. Yoh taught Lenny. "THE HARD WAY".
How come nobody has mentioned Yoh and Zeke's final fight in the anime? Needless to say, it was totally wicked.
Yoh: "I think this is what it's like to be Shaman King."
And Yoh and Amidamaru proceed to do what could not be done in the manga and kill Zeke by slicing him in half with a single slash.
Don't forget the rest of Yoh's friends attempts to stop Zeke.
Len, pissed off at Zeke for absorbing Yoh's soul doesn't even manifest his third new Spirit Control, yet uses his full-powered Golden Thunder on Zeke anyway. And his Ultimate Rapid Hyper Tempo Assault on Zeke's Shikigamis was bad either. He even uses one of his manga's newest Over Soul's attacks, God/Machine of War on Zeke.
Yoh's FUCKING ENTIRE GROUP of friends went bad shit on Zeke, even though most of their efforts were wasted. So Zeke takes Anna's Shikigamis when she tries to use them against him. All of Yoh's friends recklessly attack them and failed, while Morty is watching his friends, questioning their actions. So what does he do? He and Mosuke decide to use Spirit Control on his laptop to forge a hammer and strikes the Shikigamis. Morty's dub finishing line settles it.