Lets say that in gen III game there was a pokemon that its highest stat was sp attack but in the new games it changed and its highest stat is attack now
did that ever happend with any pokemon ?
No, I'm pretty sure that can't happen.
A pokemons stats are the same throughout every game no matter what game it's in.
Pokemon moves, however, do change their power in different games.
No it wont and shouldent happen. check again.