Dustox is the only Poison-type Pokémon that evolves from a non-Poison-type. Thus, if a poisoned Cascoon evolves into Dustox, it will keep the status ailment.
Whoa! I never knew that... The Wurmple thing was interesting too. If these funfacts stay as interesting as they've been, this won't be a lame contest after all! Also lol @ the Igglybuff fanart.
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Bunny... :3
http://img.imgcake.com/baronvontoast/0413121622bjpguh.jpg