Based on my fan-made AU of Pokémon call Dustmon.

After dozens, if not hundreds, of humiliating defeats against the player (who keeps resetting), Kieran finally breaks his usual calm. He realizes the only solution is to strike first and take matters into his own hands. But instead of letting his Pokémon fall, he chooses to use them in a much darker way: he overtrains them, forces them to battle to exhaustion, and even to kill.

Kieran becomes a pragmatic and desperate predator, ready to completely empty his world to prevent the "Genocide Route" from continuing.