If you have any specific criticisms, please speak up as I am very open to the possibility that I may be overlooking or misweighting something!
Anyway, as promised, here's my general feeling about the characters overall!
Crono: Well, I think Cmdr said it best. The game goes out of its way to keep Crono useful while he's forced. Early on he's one of the best, if not outright best PC thanks to good stats, and a share of the best earlygame random-sweeper, Rocket Roll. He starts to fall off somewhat, but a couple of 65,000,000 BC dungeons really reward his lightning. Right up until the Ocean Palace the game seems to be trying to keep him relevant. Then he leaves, and when he comes back, he kinda lacks compelling reasons to be used. He's got a bit of every type of offence, so he's almost never the worst choice, but he lacks utility, his speed stops mattering, and his damage of both types is fairly outclassed. I sorta think he averages out to "okay", though depending on how you weight his performance while forced and his performance while optional this could fluctuate.
Marle: Once I got Haste I realised pretty quickly that this would make Marle pretty much the objective pick in every boss battle that didn't totally fail for HP (e.g. Lavos Spawn) until Haste Helms (which have their problems against Lavos anyway). She doesn't quite double party offence due to the turns that Haste requires to cast, but she's not terribly far from it, especially for battles which go longer... and also has a great performance boost to your healing/utility, something no other character really does to the same degree. So Marle's in-game use is pretty much "Haste/10"; she's rarely great for randoms (Ice Water spam in Magus' Castle aside) but her performance against bosses is great, so as long as you're running at least four PCs she should definitely be used.
Lucca: Straightforward enough. Lucca starts mediocre due to bad speed and some fire walling, but then getting magic and Taban gear makes her suddenly worth using, especially for Denadoro. After that she starts to fall off again. She goes through a pretty bad spell of techs (Napalm isn't great, Protect sucks) but then Fire 2 vaults her into having the best MT and she really takes off with Mega Bomb and Flare lategame. Just... by far the best PC against randoms in the last sections of the game, and pretty great against bosses too, between the high damage and MDef. So she's a project PC, but one for whom the payoff does feel worth it overall.
Frog: Sadly, if there's a real blip in my general feeling that "CT PC balance is good stuff", it's Frog. Okay, he has the decency to be excellent while forced (Ice Water is awesome) but from there on... there's just very little reason to use him. Other characters have better healing, his damage is bottom tier aside from Marle against bosses (and Marle more than makes up for this), and pretty poor against randoms too usually. Frog just struggles to ever find a niche. He's not so bad that you can't use him if you like him; in particular, he shares Crono's trait of never being walled tooo badly by anything (so his damage is at least consistently mediocre!). But honestly I can't see a good objective reason not to drop him after Magus' Castle and never sink another point of TP into him again. Oh well.
Robo: Robo's always really good at something. However, it's usually just one thing, and that one thing changes. Early on, Laser Spin and Rocket Roll are your best MT, and your best way of sweeping randoms. This gets obsoleted around Magus' Castle... but then he picks up Heal Beam, making him a very solid choice for bosses. That falls off towards the end of the game as you get Megalixirs, but he gets the Crisis Arm Uzzi Punch for the best ST damage in the game. So Robo always has -something-. The issue is he's not great against bosses early (worst ST magic damage) and not great against randoms mid-to-late (lack of good MT, speed kinda hurts a bit midgame). This is sorta why I think I overrated him. Being good (but not amazing) in one area of gameplay and mediocre in another doesn't actually add up to a super-high score. The one exception to this is once you hit Level 50, his damage just takes off to the point nobody can match, so that's probably why I remember being really impressed by him. He's still decent, but I can't say I really consider him in the running for MVP.
Ayla: Is Ayla said MVP? Hard to say. She's not perfect, of course - she spends much of the game getting walled by physical tanks and unable to target multiple enemies by herself (and lacking any outright MT dual techs at that). She also starts out behind on techs in general. She gets some ST smash that keeps her kinda okay, but it's not really enough. However, as soon as Crono leaves, she takes off. Her uses on the Blackbird are obvious, then her ST damage smashes Lavos Spawns, and from there on she's got great physical damage, double techs for MT if she needs it, and loads of stuff to steal which keeps her relevant even if Lucca is one-shotting things. The last few bosses all calling for ST or physical further helps. Just a great overall PC in the back end of the game... which is kinda surprising given how the endgame de-emphasises base speed. But then again, Ayla is part of the reason why this even happens. She did end up with the highest overall score, weighting all sections equally.
Magus: Magus is also very straightforward. Basically, he's a high-end random sweeper. Sure, Lucca eventually surpasses him due to Flare and negating his speed edge (plus any elements besides fire being superfluous late), but Magus is still consistently good at what he does after he joins. What he does not do well is damage bosses, for the most part. Dark Bomb isn't nearly as strong as I want it to be (animation hype goes >here<) and he can't use dual techs to increase his variety. He does end up with #2 magic damage by the end, though, which is something. Perhaps the bigger thing recommending him for bosses is that Magus is secretly the game's tank. With enough Def/HP to not fear physicals, loads of MDef, and the Nova Armour option should he opt for a Haste/Safe Helm, he's probably the hardest character to kill in boss fights for any given equip setup, and that is cool. I don't think it's really enough to have him see use against bosses, though, but it is something. Anyway, solid enough character to use, though if you're willing to put up with some somewhat inferior randomslaying for 2-3 dungeons, you can get by without missing him thereafter just fine.
