Formation Event Pointers

It took me a bit of reading to understand what I was seeing, but the post from Lenophis is totally it. The formation events start at D0/FD00, and they are $18 bytes each. The "Cyan Fights Alone" ones are:

D0/FD78 (Cyan 1) 00 FF FF FF 02 02 70 50 30 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
D0/FD90 (Cyan 2) 00 FF FF FF 02 02 70 50 30 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF

The format for these flags is something I'm still working out. Lenophis's notes are not correct for several of the bytes, but I've only identified the use for the 5th and 6th byte so far
The 5th byte says "Which actor slot should I use?" This will bring over that character's HP/MP/Lvl and all of their equipment, including relics. This will cause the character to DISAPPEAR from the normal roster.
The 6th byte says "Which sprite should I use?" It is possible to mismatch this, so you could have a character use someone else's sprite. IE - they could fight the battle as a generic soldier, and then after the battle reveal that they were (insert character here) all along.
The 7th byte is correct. It says which boss script to use (add $FF to the monster number for bosses).

So, some examples of bytes 5/6/7
01 0F 6E - Locke shows up looking like a merchant, using Phunbaba's attack script
08 0A 00 - Relm shows up as a moogle, using the Whelk's attack script

So yeah, this blows open the doors for guest characters.