In diamond will swinub eventually evolve into mamoswine or stop at piloswine?
How about in platinum?
Swinub will first evolve into Piloswine. Then, once you have met the requirements (having it learn Ancientpower), he will evolve into Mamoswine with an additional level up.
As long as piloswine learns anicent power(can only be learn through move relearner so you need an heart scale) it will evolve into mamoswine upon growing a level with aincentpower in its moveset. But this is only for gen four games and up