Character models picky about what costumes they go over?

[Aura Sphere]

Ok here's the weird thing. This Knuckles model here

http://forums.kc-mm.com/Gallery/BrawlView.php?Number=29543

That I've been using forever, stopped working when I put it on Jigglypuff's green costume, FitPurin02. I originally had this Green Knuckles skin:

http://forums.kc-mm.com/Gallery/BrawlView.php?Number=29232

on FitPurin02 and I had the SADX Knuckles on FitPurin04, the white one. I wanted the SADX Knuckles on Green so he'd be picked for team matches, but he freezes whenever I put him on the green costume file. Should that happen? Is it possible for a character model to work on one costume slot and not another? The green Knuckles works on any slot as far as I know, but the SADX one seems to only like the white slot, or at the least it hates the green one.

I seriously just don't get it. I mean I've heard of some models/textures not working with certain PSAs, but not of any models/textures not working on certain specific costumes slots. Is that even a thing or have I come across a freakish "computer programs play by their own rules and don't make any logical sense" kind of problem?

[Spex130]

Jigglypuff's green slot has specific rules for importing. If the model isn't SPECIFICALLY created for the green slot, it doesn't work.

As I don't really mod Jiggs all that often I'm not sure what the specific rules are, but that's your problem. It just has to do with some special property of the green hat. More bones or something?

[Aura Sphere]

Oh is that it? Well ok then. I thought something was messed up. I guess no SADX Knuckles in team battles then. Unless someone eventually makes it for the green hat. At least I know it's supposed to BZZZZZZZZZZZZZZ if I try that lol.