Re FF9 speed: Yeah, FF9 speed (like many ATB speeds) isn't as good as it seems due to wait-times and animations and the like. I'd use it for initiative, but would damp it way down for double turning, meaning Garnet is actually only mildly above average. Maybe Ike doubles after all, even holding doubles against FF9 speed? Interesting, I'd forgotten that.
Gatewalker: So you see a fast non-FE character as being able to CTB double AND FE-double a slower FE character? Or do you throw out the CTB doubling vs FE and just have any doubling that goes on being FE style?
Not aimed at me, but absolutely. Being slow in FE sucks and means you get doubled on any attacks, and being fast in a CT based system rules and gives you extra actions to double with. The downside is that doubling only works on physical attacks, at least to me. So Jude can double his physical against Oswin all the time, but it'll just tink anyway; not sure I'd let Jude double-Assault Buster Oswin constantly, as a lot of special moves become very strange if doubled. If it's a grey area on damage-inflicting skills, it's clearly black for anything else - status attacks don't get double chances against slow characters in-game, IIRC.
Rozalia, Re Meryl: Yeah, scaling against nigh-helpless guests is definitely a no-go (AtL4 cast is suddenly thrilled about Lillia bringing down the averages?), so Meryl is irrelevant and Raiden has the same HP as Snake (at least in 2). Also if you shoot Snake with a machine gun he tends to die pretty quickly, Snake vs. three guards with machine guns is a loss, while Cloud can take like a bazillion hits from three Shinra MPs who are a total joke.
If you absolutely had to have a consistent interpretation of Snake that was flavorful, he'd probably be vaguely Belial-like? You have to use "hit everything" damage to get him. He "uncloaks" three rounds or so in (so you have time to buff while Snake is hiding and sneaking up on you if you don't have MT), and once he fires once for big damage, if his opponent is still alive (no weak points?) then Snake gets pounded into dust. But yeah, Snake is not getting ranked, so academic.
Actually, another amusing headache would be Diablo from Diablo II. Great durability, but I think we'd have to assume competent control of the character, so he's got like a 15% chance to hit with any of his attacks. Totally owned by evade of any kind, Lyn would destroy him much like Bow Amazons do in-game, but a decent slugger against "large" bosses who can't evade well and are big targets.