I'm not going to dig it up, but the basic concept was that they had very poor base stats and very low skills, but when they were in a party, they had access to any ability that another member of the party used. Magic costed no MP, but was limited by a global recast timer through a Mimic Magic ability (~20 seconds, I think). I also gave them AF that gave them a set of abilities that could mimic another party member's equipment in the same slot. e.g., Their AF weapon (a kendama), came with the ability "Mimic Weapon", which would mimic the stats of the target's current weapon.
It would have been really fun to play in a diverse party just to try to optimize the usage of all the different skills. At the same time, it wouldn't have been overpowered (though even if it were, it's not like a party full of Mime's could do much of anything). Or at the very least, it would be no more imbalanced than any other class, and as always, it wouldn't be difficult to balance just by changing the numbers a bit.
Ok, now we're going to get slash fiction of Wint x Kachi somehere... rule 34 and all...
Never confuse your inference as the listener for an implication of the speaker.
Good games are subjective like good food is subjective. You're not going to seriously tell me that there's not a psychological basis for why pizza is great and lutefisk is revolting. The thing about subjectivity is that, as subjects go, humans actually have a great deal in common.