Giant, round space cat... oh lord. Now to be fair that episode of Max is one of my favorite of that particular series, mainly because a the crazy, comedic stuff that made it a chore to get through Max actually worked. But I don't see how it's going to work in X.
As far as Nexus, one of the points of that series was the "more than one host/Dunamist" dynamic before the show started. Now those pictures are of his Junis red form, which as far as I know he can only achieve if he bonds with somebody. I haven't watched the Ginga S movie yet so I don't know if they changed that. Soi t might be possible he bonds with somebody in X's universe for that particular story.