Infinite Alien X is much bigger than Alien X, and about as big as Humungousaur's giant form. His three horns on his head are now one big horn, symbolizing that the three personalities are now one, and he is more muscular. His Omnitrix symbol has three spikes, as do all BTMT Infinite Forms.
He hasn't appeared in the series itself, and probably never will.
Carter 10 it runs in the family
- infinite power part 2 ( mentioned by carter )
- Secret of the sacred forever pottery ( mentioned by rook )
- ( he will probably never appear due to it being too powerful )
- Carter Smith the series creator announced on august 23rd 2013 that Infinite Alien X form will appear by the series finale
He is a playable alien in Ben 10 Multi Trixes: Escape From Eon! for the end bonus stage only, in which you must stop Eon. That is his only real BTMT appearance.