If Zero and Null met how long would it take for Null to notice Zero's kind of a creep?
Not long.
If it was a Vs fight. It'd be a flip of the coin of whether their powers would cancel each other out.
Zero has taken Scott's optic blasts with no injury whatsoever.
Null could stop Scott from shooting MORE optic blasts but unlike Zero, Null has yet to make physics his bitch and would still probably be knocked back by the contact with the initial blast.
Considering Null is immune to mutants with pheromonal powers, Zero's addictive touch would logically have no effect on Null.
So in all likelihood it'd be just two dudes... I don't mean to throw shade but Zero's getting his ass kicked.
Zero is a quick thinker but relies on his harem to do a lot of his shenanigans and some of his girls clearly show increased physical strength over him.
Null acts on his own, and it's partially the reason he ends up in the hospital, but a dude with green skin vs a Juggernaut and Sentinel? Yeah with Null's one on one training with his girls that are personalized compared to Zero who simply performs drills and gets hunted by Wolverine. Null would have the skill and fitness to take down Zero with a single punch to the throat.