Paydirt. Check
this out. What does this look like to you? If you answered "Kid spazzing out," award yourself a cookie. That's exactly what's happening. Anyone care to guess why? For once, the answer isn't "HyperGeek was messing around with the animation data." Not directly, anyways.
As mentioned in the video description, I believe Kid's model is trying to use Serge's attack animations. Yes, she's also really freaking out, but my guess is that she has more joints than Serge (Her animations seem to have more than eight bytes to identify which joints animate.), so the game is interpreting the data in a really weird way. I'll let you guys be the judge of exactly what's going on there, since I may just be seeing what I want to see, and there's some odd side effects from this that I wouldn't expect to happen if I'd done this right. Here's what I did to make it happen.
Short version: I changed the data at address 0xFF70 from 0xD45202BC to 0x7F520296. Try it and see for yourself, it'll save you a lot of trouble reading the next few paragraphs if I'm (very likely) wrong about what I'm looking at.
Long version: Vehek located the sector where at least one of Serge's attacks should be, along with the eight bytes that start it. The attack in question (based off searching for those eight bytes) seems to begin at 0x129470C8. Working backwards from here, there's something that looks like a standard animation header (number of animations and pointers to them) at 0x12946A30. Some fiddling with the animation here confirmed that this does point to the animations for Serge's attacks. Now, work backwards from
there. Somewhere in the neighborhood of 0x1293F800 is what looks like either another header, or at least some pointers, one of which seems to be pointing at the animation header. (I think they start at 0x1293F808 or 0x1293F80C, but I'm not exactly sure.) 0x1293F800 is the start of sector 2527F, which Vehek identified as being where Serge's attack animations are. I can pretty much verify that the animations themselves are not there, but the fact that path to find them begins in that sector makes me pretty sure that either this whole mess is lining up or it's a whole bunch of coincidences, I'm not sure which.
Anyways, if you do a hex search for 7F 52 02 (Which should be how that sector number would be referenced in the hex, right?) the first result should be at 0xFF6C, which looks to me (As usual, I'm operating more by feel than any sound scientific principle.) like it's part of the table of contents. If you repeat the whole working backwards process for one of Kid's attack animations, I believe the sector where the pointer to the animation header occurs for her is 252D4. As luck would have it, the next entry in the ToC references this sector. Changing that entry to 0x7F520296 (In other words, making it point at Serge's data instead of Kid's.) caused the results you see in the video.
Today's experiment also revealed some issues with the above, even if I really did manage to trip over the attack animation pointers. Changing the entry in the ToC for Serge to match the one for Kid causes Serge to lose the ability to attack. You can still select attack and choose a target, but there's no cursor to allow you to choose your attack level, so you can't actually select any of them. Trying to change Serge's entry to either of the two after Kid's (These would presumably be Guile and Norris) causes the game to crash and burn when you select a target for his attacks. It wouldn't surprise me if this was the case for the other entries as well, but I haven't tried yet. Changing the entry for Kid to match the next entry (Again, I'd assume this is Guile, but I haven't checked that.) causes her to lose the ability to attack, but strangely allows Serge to attack if his entry has been changed to what hers normally is.