Yes, the developers for Pokémon Colosseum (and Gale of Darkness) actually uses recycled N64 models from Pokémon Stadium and its sequel Pokémon Stadium 2; some are actually changed (Azumarill, Ampharos, Sunflora, Magnemite and Magneton (fainting animations), Psyduck, Jynx to name a few) and most are kept. Developers of Colosseum didn’t even bother to use N64 cries in there either (they didn’t)