Venopede/Scoliopede as well as Petilil/Liligant
When I saw Venopede I wasn't impressed. However, after seeing Scoliopede, I started t want to give it a try. It's a pretty rad Pokémon. I'm glad I gave it a try.
With Petilil and Liligant, same thing. I did think it was just some weak grass type...