Quite a few during Super Mario Bros. when he performs surprisingly good feats, with or without save states.
A good example is, while trying to get past the dreaded Hammer Bros., he accidentally kills both at once, jumping up and hitting the block one is standing on, which knocks him down onto the other one's head, killing them both in a split second. And he does this twice in a row.
While playing Super Mario Bros. the second time, he beats World 7-3 without dying, using save states, or even getting hit, despite plenty of moments of nearly falling off the edge.
In Lost Levels, he knocks a Koopa Shell forward, killing a line of enemies...then it bounces back off a wall and kills more that weren't in the way, giving Zero a 1-Up. Then, Zero accidentally stomps a Koopa and gets another 1-Up instantly after.
In Minecraft: The Walls, Zero, without saying anything, finds an obsidian construction in their quadrant, walks inside, deactivates a trap, and swipes nine diamonds from a chest. He later makes them into diamond swords for his team.
The ultimate awesome moment for the three-on-three match would have to go to Fury, who manages to kill RLYoshi and Zero by himself when Frank and John were already dead, and Bridgett had mysteriously left the game.
The winners of each match are as follows: Fury in the three-on-three; tie between Fury and Zero in the first two-on-two; Frank in the second two-on-two. Each time, it was close, and pretty epic.
If you count up the kills, Fury and Zero tied and killed the most people. Second place? Yoshi!
In his Pokemon Red LP, he catches Mew via glitch. It learns Mega Punch during some offscreen level grinding. He now has a Mew with a Falcon Punch.
In a trainer battle in Pokemon Red, he forgot to switch his Pidgeotto for his Arbok, and his Pidgeotto had only 7 HP remaining. He got into a trainer battle and won with his Pidgeotto. With 1 HP remaining by the end.
In The Walls 2, who wins the round? RLYoshi, who singlehandedly killed John, Fury, and Zero, the latter two while poisoned.
Earlier on, Yoshi and Zero come across the diamond ore in the middle of all the walls...only to realize they don't have an iron pick to mine it with. So Yoshi decides if they can't have the diamond, nobody can. Cue breaking the blocks with a stone pick just so John and Fury can't take it. And revealing the chest containing goodies inside.
Clearing all of Super Mario Bros. The Lost Levels, in a single video, without using any warp zones.
In Pokemon Crystal, he manages to take Whitney out rather easily; he has his Quilava use Rollout (known for being the Signature Move of Whitney's Miltank) to take out her Clefairy, building power, and then one-shots her Miltank as soon as it comes out.