Here are a few inspired by my "RealDex" project, where I take photos of things that remind me of Pokémon or may have Pokémon based on them. (Tangela's entry, for example, is based on the parasitic "witch's hair" vine.)
Lickitung: There are contests measuring the speed at which Lickitung can launch its massive tongue. The current record is 15.7mph.
Lickitung V2: Lickitung can launch its massive tongue up to 15.7 miles per hour. It prefers damp habitats.
Tangela: Because its vines lack leaves to photosynthesize, Tangela latches onto other plants to steal nutrients. It's dreaded by Grass-types.
Ditto: It can mold its body into any shape. Ditto's color varies depending on the minerals that occur around it.
Vibrava: It's believed to have been one of the very first Pokémon to develop wings. Many anglers use lures shaped like Vibrava.
EDIT: Added an alternative description for Lickitung.