>>46683103Pre Gen 6, Ice and Poison would be swapped.
Ice served as a cool endgame type and the only real check to Dragons. It was always nice to have one on your team because the Champion of a region usually carries a pseudo. Meanwhile Poison was literally only SE on a type that already had four other weaknesses.
Post-Gen 6 and the introduction of Fairies, Ice lost its niche and Poison's coolness factor went way up.