It was only Kain/Cecil that I tested this on. I'll test it with a full team to see what happens...
Alright, I have a team of Dark Knight Cecil, Palom, Rydia, Yang, and FuSoYa and allowed everyone to equip the Avenger.
Yang (Top)
Rydia (Upper)
Cecil (Middle)
FuSoYa (Lower)
Palom (Bottom)
So far it seems that FuSoYa will only copy Palom. Hmm... might this have anything to do with Palom and He both being capable of Twin Magic? (When used together the two cast W. Meteo) Curiously W. Meteo doesn't take any MP. Bot sure if that was mentioned at all.
So not only do they Mimic the school of magic used. They will go as far as to use the Spell that was in their spot (I had Palom use a Modified Protect on himself that was in his second slot and FuSoYa reacted by using the spell that was in his second slot).
If the character has a spell they can't afford in that slot that is mimic'ed the game will surprisingly say "Not Enough MP" after the casting is attempted.
It is not tied to Slot, it is tied to character. Specifically with the Avenger on FuSoYa he is tied to Palom's moves, no matter where Palom is placed as bizarre as that seems. But if it's Palom... I wonder...
Do you think that maybe they had originally intended the "Twins" behavior to Literally mirror one another? (I'll edit this post as I find out more)
Hmm, this is peculiar... I put the Avenger sword on Palom now and the first turn he will mimic Cecil's actions. The next turn he will mimic FuSoYa's actions...
Third and Fourth turns he still seems to follow FuSoYa, but the fifth he follows Cecil.
Sixth he follows Cecil, seventh he follows FuSoYa.
If. when he's mirroring Cecil, Cecil uses Dark Wave, he will start a Twincast with FuSoYa and cast W. Meteo.
If I try to jump with Palom attempting to mirror Cecil, the game crashes.
Yet when Cecil uses Peep, Palom looks like he does something, but nothing happens.
When the character uses a spell outside the limits of the Mimic's own spell list they will attempt to cast a White Magic Spell which says "nothing happened" (Likely Spell 00)
Rydia will mimic FuSoYa for a couple of turns and then change to Palom, switch to Cecil, then back to FuSoYa. I have no idea how this order is determined, but it does not seem random.
After two turns of mimicking Palom, Yang stopped acting all together, regardless of who acted.
Dark Knight Cecil, after mimicking FuSoYa consecutively for four turns, then switched to Rydia.
So that's been interesting. Now I'll try out the twins, to see how that all reacts, and then move onto the final team since that's the only time to have the Avenger.
A team of Palom/Porom/Cecil, will have Porom mimicking Cecil on the first action, then Palom on the second. Then Cecil for a few more, than Palom again. Hmm... I'll give the Avenger to Palom and see where that goes.
Interesting... when Palom has the Avenger and Porom attempts to use Twin, they both move to use it, but nothing happens. It seems that with two people the game will mimic each character, or at least that's the case with Palom and the Avenger. When Cecil took an action, he took an action, when Porom took an action, he took an action.
With the normal group of five, Paladin Cecil with the Avenger will mimic Edge for several turns, and then mimic Rosa, then Kain, then Rydia, then Edge for three more turns, than Rydia, than Rosa, than Rydia, than Edge. (So on and so forth)
The rest follow different patterns in that regard.
So it would appear to me that this was intelligently put together, but something must not have sat right with the code. Testers may not have liked the particular patterns or some such or possibly they just never finished fully programming its functionality. I do know though it is far too elaborately put together to be a simple glitch.
We have EVEN MORE themes now, but some old ones are gone...