Shouldn't be a problem. I don't think you will need ID. For the past several years I have purchased both my pass and my brother's. They never once asked for ID for myself or my brother.
When in doubt: Duct tape it.
Giant Diglett will return!
Possible Future Cosplays:
-Zapdos Original design (humanoid)
-Unown Original design (humanoid)
-Marika Kato - Pirate Captain