Ugh. Another bug sporadically appeared. If you switch anyone out in the 2nd slot, they become completely effed up. I don't even know what to do with this now..
Edit: The bug is only present in areas where 8thy is loaded. If you have 8thy in the active party and switch anyone out in any slot from the reserved party, it'll kill itself completely.
Edit 2: I found the routine for the characters...004226 - C9 00 , this loads Crono, then later there's C9 01, 02, 03, 04, 05 and 06. This only loads characters 1-7. Changing it to C9 01, 02, 03, 04, 05, 06, 07 results in it loading all the characters except Crono perfectly. We have to re-write the routine a bit and add it on for the 8th character and then everything will work.