Source

Of note, the Yuma Deck concept has been updated to require the Extra Deck only contain Number, Gagaga, Gogogo, Dododo, and Zubaba monsters. For those paying attention, there aren’t any Dododo Extra Deck monsters.

Possible spoilers for upcoming cards?

Edit:
It has come to my attention this update was last made on August 15th, 2014, but it does seem odd to mention Dododo when there aren’t Dododo Extra Deck Monsters… How curious.