You really cannot leave out Kazuma Kenzaki defeating the Category King of Spades by ditching ALL of his special techniques and abilities and shattering the King's invincible shield with his bare hands before taking the King's own weapon and defeating him with it, then proceeding to use the power-up he gained in sealing him to save a crowd of people from the newest Trial monster.
Tachibana's final battle with Isaka.
Tachibana deserves an extra one for this moment: having spent quite a bit of time being worried about his body breaking down, he momentarily seems to be Isaka's servant in exchange for a certain plant that makes him more aggressive and removed the risk of destroying himself. However, once he gets the Category Ace card Isaka wanted, he IMMEDIATELY turns around to battle him. Even if he gets his ass kicked, that was pretty damn cool. And it gets better: after his defeat, he finds Sayoko dead, killed by Isaka. So what does he do? Pretty much walks traight up to Isaka's front door, ask him if it was him who did it and straight up shoot him in the face when he admits it before any kind of kung fu fight can ensue. That's pretty damn awesome.
The battle with Trial G. For the first time, the four Riders all fight together, ending with Wild Chalice and Blade King Form obliterating it with a combined finishing move.
Episode 44: How the four riders lure out the Titan Undead.
The Movie ends on a rather epic battle where it ends with Kazuma cutting Jashin 14 in half in his King Form. Mind you, Jashin 14 is a massive beast, about four times as big as the Elasmotherium Orphnoch.