While abusing field effects to your advantage is good, sometimes the after effect of the fields could also hurt you. I remembered when I used fire against Corey and all grounded Pokes are hurt when switched in. Even though I avoided being poisoned and Venoshock abuse, the corrosive terrain after that also power ups his Pokemons. With Noel, corrosive field sure can chip down bit of his tank normal types while removing the heal effects.
Bringing rosters than can change terrains to your advantage strategies is good but for me it's quite difficult to find a good timing for switching considering how high the stats of Gym Leaders' Pokemons and it could be one shot on switching in.
So, it's either adapt to the terrain, take advantage of it and fight fire with fire or just destroy the field. At least, that's what I would do...
ORAORAORAORAOROAROARAORAORAORAORAORAORAORA !!!