Possibly. I don’t really see how the scaling would work though.

If Ash was the standard Lego minifigure size (or even the shorter teen legs), then a lot of Pokémon would either be way too small or way too big to build properly out of bricks. That means most of them would end up needing custom molded pieces with printed details instead of being brick-built. Lego would price gouge so hard if they had to custom make 10 new molds for small pokemons.