Sudowoodo is actually a genius

So, Sudowoodo is a Rock Pokemon posing as a Grass-Type. Coincidentally, Rock is super effective against most of Grass’s weaknesses: Fire, Ice, Bug, and Flying. Even though it isn’t super effective against Poison, it still resists it. Because the first two generations of Pokemon have an absurd number of Flying type Pokemon, Sudowoodo could actually be using this to its advantage, pretending to be a Grass type Pokemon to lure in and catch Flying type Pokemon, while keeping Ground type Pokemon away.