Lets clarify what happens to Cloud each game after FF7, ignoring blatant cheap cameos like FFT.
KH: Has the whole "Sold my soul to Darkness for Power so I can find someone!" nonsense, angsts, what have you. The first hint of Emo!Cloud...
This applies to KHCoM too which mostly just retold the exact same story <_<
FF7AC: This is where the Emo thing really took off. All he does is fight or basically angst and brood about how his life sucks. He doesn't smile pretty much the entire movie until the end, and it basically ignores all his development, claiming he'd regress to something based on manners that he very much dealt with in FF7 (he even went out of his way to acknowledge that he's done with them, being part of his big End Disc 2 speech and all.) It really ignored everything that happened with his character.
KH2: Emo!Cloud appears yet again, this time going all "Watch out for Sephiroth" but then Sephiroth comes and...basically mocks him for everything Cloud told Sora to watch out for, pretty much saying "Cloud, you're an idiot, I'm not the loser whose brooding in darkness, you are." It says something that Sephiroth shows more personality and was friendlier to Sora than Cloud is. I would say that about Squall too, except that KH1 did go out of its way, in his bio, to state that Squall changed his name to Leon specifically to disassociate himself with his former self, so we can attribute the change to that, if nothing else (Leon is a lot more likable and friendly than Squall.)
Dirge of Cerberus: mostly exists for an action scene, has a generic chat with Vincent, etc. Yeah, probably doesn't really count.
Crisis Core: Cloud's more just kind of modest and shy here, rather than Emo. He doesn't really come off as being recognizably Cloud, beyond the design, but then, its actually justifiable here; its Cloud Pre-Nibelheim, after all, someone we never actually saw and only had vague hints what he was like, so yeah; and he's different in a way that's not "UGH HATE" like AC/KH Cloud is.
Dissidia: Oh look, they FINALLY did their homework and FINALLY realized that Cloud isn't an Emo little bitch, just rational and more duty driven. He actually shows signs of being friendly in this game, and looking out for others, rather than just going "my life sucks." Not a perfect representation of Cloud, but then its hard to do so with a character like that in a manner of a half hour worth of cut scenes, so frankly, I'll take what I can get, as far as accurately portraying him.
So yeah, in short...
Crisis Core he was different, but for justifiable reasons. Dissidia, he was about as good as you'll get in that, as to accurately portraying him. Advent Children and Kingdom Hearts? He will make you hate yourself there.
EDIT:
Oh yeah, from what I understand regarding Advent Children...
The movie was mostly made just on the concept of looking damned cool and visually awesome; basically, emphasizing the ACTION more than the MOVIE. Which, being an Action Movie, isn't such a bad thing, and the movie is fun to watch if you turn your brain off (which if you haven't done already, there's something wrong with you.) The plot was mostly just a thin BSed thing to attempt to make some coherent sense other than just explosions and nothing going on, cause you kind of need something in the movie, but uh...Nomura isn't a writer, as we know, so what'd you expect? It sounds like AC: Complete does fix up some of AC's blunders, but I honestly can't speak for that.