As I recall, Rock is in a different format from other characters. His gameplay model isn't stored the same way as the various NPC and cutscene models in the game... and notably his models that you can view in any of the various tools out there, are cutscene/NPC models, not the main gameplay one, for that reason. The first game was like that too but in an even weirder way. It probably has something to do with how they chose to load the parts on the PSX hardware, without it bogging down. This wasn't a concern for most characters who might only have one alternate hand gesture or something at most that could simply be loaded but hidden until needed at minimal resource cost.

I can't find Megaman with helmet and that big blaster on his right arm. That's the model I am looking for, does anyone know? I have found every other model like Bonnie, bunch of bosses and enemies, Wily etc. but not Megaman himself (I mean I found him but he doesn't have the textures and the rig like the others)

oddly enough it was the fact that the models had baked in lighting that led me to finding the vertex data in the first place. Although EChiz deserves the credit for decoding the 10bit ints that make up how the coord data is stored...
Man, I still break into a cold sweat thinking about all the crap I went through importing the characters when I did. Unfortunately there's no easy way to determine what file has what character, else I'd upload a few myself... well, that and ensuring the files are of adequate release quality... which is a clerical nightmare in its own right.

Super weird to see the models with somewhat proper shading/lighting.