I want to add a couple things. Aggregor was going to absorb a baby Celestialsapien. Osmosians absorb
1/10 the power of their source of energy. I find it odd how Aggregor would be considered "omnipotent" with Celestialsapien DNA mixed with five other alien's DNA but Atomic X would be a measly High 5-A. That’s pretty nonsensical. If you want to talk anti feats, Maltruant (who has an awful profile) is the only person to ever harm Atomic X. None of the future characters are even able to harm Maltruant.
Seriously watch the fight, he completely blitzed and manhandled everyone on the battlefield. Even if you want to say they can stagger him, they're still
comparable to Kevin 11k, who should be 1/10 Alien X because he has all of Ben 10K's abilities. It's even consistent when you consider Kevin 11k is superior to
this version of Kevin, who should also be 1/10 Alien X because at the time Ben
had access to Alien X and he wasn’t locked like he was in the Ultimatrix. Also before anyone call it an outlier, it was
kevin's plan to momentarily capture Ben, so he was definitely holding back and wasn’t trying to kill him.
I think the future Aliens should be low 2-C with Maltruant, Atomic X and Alien X being at least low 2-C. Low 2-C for future characters is hilariously more consistent than High 5-A by a long shot. And it's not like they fully scale to Alien X anyway. Call me a mad man, and I wouldn’t blame you. After all It's a Mad Mad Ben World.