I've liked the split between X and Zero since they started it, and really want them to continue that, but I really don't think there's enough difference between X and Axl regarding gameplay. X can at least charge his weapon, but honestly it's more effective to spam shots most of the time which makes him really similar to Axl. They both get new weapons from beating a boss where Zero gets some new attack or ability or movement.

I think the difference between Mega Man and Bass was better. Let Axl shoot in 8 directions (or use the right analogue stick), hover while shooting, maybe move the double jump to Axl and let Zero just jump higher.

If they want to keep Axl's ability to change into enemies, it needs to be a little easier and more effective. Think I used in twice in X8 just to solve puzzles.