Vexen. Sora hated the guy for what (he thought) he did to Riku, and even he was horrified by the cruel way Axel dispatches him (while he's begging for mercy, no less!). Not helping matters is the fact that he was trying to warn Sora about the trap he was walking into, shortly before Axel showed up.
"Forgive me, Zexion... This was a fight I should not have started."
Zexion. Possibly the most brutal death of all the Organization members. Everyone else just died (some were more vicious than others; here's looking at you, Vexen). Zexion? He was strangled to death, his life force slowly sucked out of his body as he lost consciousness. What makes this sad is that Zexion showed himself to be highly devoted to the Organization's cause, even up to his final moments, where he's absolutely mortified by the prospect of his death. That doesn't excuse his actions, mind you, but when you put him in comparison to the behind-the-scenes backstabbing game of hot potato that approximately half of the remaining members played, it's a bit depressing.
Artificial Stupidity / A.I. Roulette: Donald's card, for the most part, is very unreliable. You could have scenarios when he would cast Cure on you two times in a row when you don't need it, and when you DO need it, he won't cast it.
He's also known to cast spells on enemies that absorb them.
Ascended Extra: Jiminy Cricket has a significantly bigger role in this game compared to others, appearing in almost all scenes.
Awesome, but Impractical: Zig-Zagged. Warp Break on Riku mode has a chance of randomly one-shotting trash mobs. However, it doesn't work on bosses for obvious reasons.
When you play as Riku, you actually get to use Dark Aura. You remember that move as possibly having screwed the heck out of you on Sora's story (not to mention KH, where it was one of the reasons Riku was That One Boss in that game). Unfortunately, when playing as Riku, it tends to fall into this category - it's unavailable for a large percentage of the game because to use it you need to A) be in Dark Mode, and B) stock three 9-cards (the rarest and strongest cards) together, and you use a fixed deck. And if you can pull it off on bosses, you'll have to get them in just the right spot for them to not dodge it or break it. Still, though, it's very useful for clearing out trash mobs.
Some sleights are that way, especially since the AI loves to cheat and break all of them.
Some enemy cards have interesting effects, but they all cost a lot of CP. This is completely inverted for Riku though.
Bigger Bad: The leader of the Organization (i.e. Xemnas), who serves as the Big Bad in the next game. You played KH: Final Mix, you already encountered him as the Unknown.
Bittersweet Ending: Marluxia, Zexion, and Xehanort's Heartless are defeated, but Sora has to go into a coma until Kingdom Hearts II in order to regain his lost memories, Riku ends up Walking the Earth (albeit with King fricking Mickey helping him (well, at least for some time)), and the Organization is still out there...
Boring, but Practical: Sleights can easily trivialize several bosses, especially Sonic Blade in the remake.
Alternatively, sleights are largely unnecessary. It is entirely possible (and not too difficult) to simply pump your deck filled with 8's, 9's, and a couple of 0's. This allows you to essentially button mash until you need to heal or break an enemy sleight, and then rinse repeat.
The Jafar Card for Sora. It allows you to use 20 cards in a row (taking away 3 if you use a sleight) without getting card breaked. Meaning, you can spam powerful low cost sleights like Ars Arcanum without getting card broken and basically stun lock the enemy until the card effect runs out. This is one of the easiest ways to kill bosses.
Mega Flare. Its the easiest way to grind Sora to max level.
Exploiting the double-jump glitch with Riku, which allows him to dodge and then directly attack from the air afterwards multiple times. The only downside is that it can only be used in Dark Mode.
Attack Bracer and Overdrive.
Dark Firaga on Riku. It's just a Firaga that's blue... but it can really hurt some enemies, especially Lexaeus. Also, it might be better to trust on its accuracy than to bet on Dark Aura.
Bragging Rights Reward: Any cards you get during a new game after completing Reverse/Rebirth mode once such as the Ultima Weapon and Ansem cards are these, because you've already beaten every challenge the game has to offer at that point.
This is repeated later in this same world, after Hades is defeated:
Sora: The games are canceled? How come?
Phil: Three words: everyone's pooped!
Goofy: Wait a minute, that was only two—
Sora: You gotta be kidding!
The Computer Is a Cheating Bastard: Sora's last 2 fights with Riku Replica has him cheat. In order for you (playing as Riku) to use Dark Aura, you have to use three "9" cards. Riku Replica can use it with any values, so long as he uses 2 of "Card A" & 1 "Card B."
However, it's possible for you to cheat against Ansem in the original. Go into Dark Mode, activate Maleficent or Jafar, double jump, then attack. You hit Ansem multiple times, and you don't deplete Overdrive or Attack Bracer's counts, while still having the effects!
My Rules Are Not Your Rules: Think you can take a bunch of potshots at the nobodies who have to reshuffle their decks? Guess again...they'll either pull megalixirs out of nowhere or float out of range and then charge. You can't do this yourself.
Darker and Edgier: Compared to the first game. Chain of Memories' continuously oppressive tone and seeing Sora becoming more and more of a jerkass as the game progresses is pretty dark when held up next to the optimistic and adventurous tone of the first game.
Declaration of Protection: Sora and Riku Replica towards NaminÚ. Even when they both discover their memories of her are fake and that Riku is a replica of the real Riku and created by Vexen, they still resolve to protect her.
Riku Replica: "What can you possibly think I ever had? Both my body and my heart are fake. But there is one memory I'll keep, even if it's just a lie. Whether it was a phantom promise or not, I will protect NaminÚ!"
Distressed Damsel: NaminÚ. Half of this distress is real, while half of it is bait for Marluxia's trap for Sora.
Evil Cannot Comprehend Good: Even though it's part of their plan, the Organization members seem genuinely confused as to why Sora would strive so hard to protect NaminÚ even though his memories of her are fake.Justified, since they have no hearts and therefore have only a theoretical understanding of emotions.
Evil Versus Evil: Many of the Organization members are working against each other, even though they're all villains.
Glamour: Namine's power to insert herself as a trusted friend of Sora's.
Glamour Failure: The screen will flicker when artificially created memories start failing.
Glass Cannon: Zero cards. They can break any card regardless of value, and against bosses can halt their sleights instantly stopping their attack and staggering them. However, zero cards in turn can be broken by a card of any value.
Interface Screw: In the Game Boy Advance version, Lexaeus knocks the screen down so you fall towards him - Don't ask how he doesn't destroy Castle Oblivion, considering he's doing this in the basement.
Jerkass: Most of the villains, but particularly Larxene and Vexen. No wonder they get on each others' nerves...
Sora also becomes one, albeit for a little one. He gets mad at Donald and Goofy out of spite and temporarily abandons them. When Jiminy calls him out on it, he tells him to shut up. However, The Power of Friendship reunited the heroes.
Axel: "Remember the order: 'You must eliminate the traitor.' I always follow orders, Marluxia."
Lip Lock: Hits the remake hard, leading to weird pacing or dialogue that doesn't match the lip movements, possibly owing to its use of pre-rendered video instead of in-engine cutscenes like previous games. The fact that the scenes are superficially identical to in-engine rendering just makes the uneducated player wonder why they didn't fix the lip flaps like in KH 1 and 2 and makes it grind even more.
Living Memory: The characters in the castle (other than Sora, Donald, Goofy, Jimminy, and the Organization members plus NaminÚ) are all memories of Sora's.
Nostalgia Filter: Discussed in-universe. Dr. Finklestein is making a potion that will show someone their "True Memories." He comments how the heart, specifically, emotions, can distort memories. Later on, Oogie Boogie tries the potion, and is driven insane by it. Jiminy Cricket muses that "True Memories" could be rather dangerous.
For Sora, it's Card Points (CP). The more CP he has, the more cards he can put into his deck and the more powerful the level of cards he can put into his deck at a time. This leads to being able to use more and more Sleights and Enemy cards in combat with ease.
For Riku, it's Dark Points (DP). Once Riku is in Dark Mode he has increased speed, can utilize Sleights, and deals more damage. His three-hit combo even has the power to stun with the second hit. DP increase the length of time(reduced by damage and card breaks taken) that Riku is allowed to remain in Dark Form.
Precision F-Strike : Axel gives a Disney-level one in the GBA version which fully cemented him as awesome in the eyes of the fans.
Axel: "Now, Sora! NaminÚ! Riku! Marluxia! Larxene! It's about time you gave me one hell of a show!"
Psycho Electro: Larxene. One of the most out and out CRUEL people in the series. Even Maleficent comes across as more sympathetic in the next game, and she's the freaking "Mistress of all evil!"
Pun-Based Title: Reverse/Rebirth. Transliterated into Japanese, both words would be "ribāsu".
Remember the New Guy: Deconstructed. Sora goes through this... except it's not the writers trying to say a new character was always there. She never was...
Schizophrenic Difficulty: Reverse/Rebirth as the game features fixed decks. As a result? Some levels wind up much harder because you're stuck with a crappy deck. Wonderland in particular only gives you 9 attack cards.
Marluxia is probably supposed to sound elegant and sophisticated, but it really just sounds like he's throwing words together in the English dub of Re:CoM. Could be blamed/justified by the Lip Lock effect.
Axel: "You give a challenge like that to Vexen, and he'll... seriously want to eliminate Sora."
Marluxia: "That would be an unfortunate denouement."Translation That'd be a bad outcome.
Vexen does this as well.
Vexen: "As if you have such a heart to speak of yourself!"Translation You're one to talk!
The Stations of the Canon: That Sora (re)experiences all of the events of the first Kingdom Hearts game (except for a certain Important Promise) is a major plot point, since he is literally re-visiting his memories (while Namine manipulates them).
Title Drop: Several times. It is explained that memories are connected, 'like links of a chain'. Thus, anyone who feels like screwing with Sora tends to lash out with one of these.
Vexen: "If you remain bound by the chain of memories and refuse to believe what is truly found inside your heart, then throw it away."
Marluxia: "Imbeciles...You would knowingly shackle your heart with a chain of memories born of lies?!"
Took a Level in Jerkass: As Sora's heart is manipulated by Namine, he definitely becomes more Jerkass compared to his original self. When Donald and Goofy show some concern for him as they approach the twelfth floor, Sora accuses them of wanting to give up and ditches them, doing the twelfth floor alone. When Jiminy Cricket calls Sora out for his behavior, Sora yells at him to shut up.
Trick Boss: Marluxia's third form in Re:Chain of Memories.
Unwitting Pawn: Sora spends thirteen floors walking straight into the Organization's trap.
Also, the 1.5 HD Remaster which has Kingdom Hearts Final Mix bundled with the PS2 Remake, and it is finally released in Europe as well.
Use Your Head: Using Goofy as a battering ram in a sleight exclusively for the PS2 version.
The Very Definitely Final Dungeon: Castle Oblivion's thirteenth floor. All the previous levels have been changed to appear as one of the worlds from Sora's memory. For the final level, all the illusions have been stripped away, and it is simply... Castle Oblivion.
Voice Grunting: The GBA version features this in battles only. The trope is applied more literally in the English version, where all voice clips containing actual words by newly introduced characters like the Organization were cut (seeing as they were in Japanese, which would jar badly with the English-speaking recurrers, of course) and only the grunts, laughs, etc. were left in.