>>44415605Chesnaught because both of the other 2 are bad.
But really, as much as people say it looks bad Cheanaught fits the "big armored warrior" archetype well. Its stats and type make sanse for it intended playstyle, and it works well in Kalos specifically when fighting the gym leaders. With STAB and some easily available moves it can beat
Gym 1 (it gets rollout early)
Gym 2 (neutral STAB)
Gym 4 (it resists the gym type)
Gym 5 (fighting is SE on 2/3 Pokemon, also resists electric)
Gym 8 (not recommended but fighting is SE)
The most important ones here are gym 1 and 2, as by later gyms you can build a team to support where Chesnaught has weaknesses. Chesnaught also does well the E4 by beating 2 members pretty easily and having good moves for a decent nimber of Diantha's Pokemon.
Grass is also arguably the hardest of the syarter types to replace in Kalos, as there are many Water types and Fire has early power picks like Talonflame.
