It goes in order; Aku Aku, Uka Uka, Velo mask, Sparx, Apo Apo. Apo Apo is the new mask that came in this grand prix update, set in a post-(apo)calyptic world. As you can see, he is a reference of both Aku and Uka's design from the most infamous games of our marsupial; Crash of The Titans and Crash Mind Over Mutant. As a fan of those games, this was really a pleasant surprise, thank you Beenox! Sadly, they still haven't fixed Aku Aku's theme. Image;