Tentaquil is a fake Pokémon. It had been first seen in a drawing thread of /vp/, 4chan's Pokémon board. When asked what it was, the creator replied "It's a Tentaquil". A romhack was later made called "Pokémon: Tentaquil Edition," in which the player's only Pokémon is Tentaquil with his signature move "Puke Blood". It's behavior pattern simply involves it standing in place bobbing up and down.
If made to walk (Like making it rideable and riding it), it will hop like most meme objects do. Philosoraptors will immediately start attacking them.