u/Cokevas

The remaining Viltrumites by the time of their arrival on Earth got isekaid to Pokémon world, they're there to conquer it but they have to do so under a tournament like format, much like Pokémon battles, only that they'd have to fight against the humans of the setting.

Do they have a chance? Or do base Pokémon human population win?

The fight is to death and every Pokémon human that wins gets a badge.