Em... which stage is the one that has only modeldata[0] to work? It soulds like the temple O.o
Well, the rule for standard stages is that, every model in a modeldata will move because the first animation in that modeldata. The others will get ignored. Other stages have more than 1 animation in a modeldata, but that's because the rel file makes the stage use them when needed. The standard one in a standard stage is the first, and only the first.
If you're using an animation to place everything in the stage, and it's used for a moving model, if the lenght of the current animation and the one for the new model you want to add are different lengths, you won't be able to make them be in the same modeldata unless you adapt one of them to be the same length as the other. This way, you could mix both animations in a single animation and make more than 1 model having the animation in the same modeldata.
But, as I said... Which stage freezes when you try to import a model with its animation into modeldata101? Modeldata101 has always worked for me. It's the most useful thing in stages, because you have always an extra modeldata to work. Moving collisions are not working for this one, but that's nothing. Having extra models with their own animations is indeed useful, some of my stages wouldn't be working for wifi room in a proper way without this.
So... Just import your model and animations into modeldata101, keeping the poketrainer model in it... And it should be done this way O.o
I will try this. although the models I wanna give anomations too are characters.
EDIT: it worked thanks mewtwo2000.