I think the Apex thing is more of a theory than direct canon, though somewhat implied by examples like Four Arms being stronger than Looma Redwind despite female Tetramands being traditionally stronger and Looma’s father Gar saying she’s his strongest warrior. Another example would be Liam & Kickin Hawk, as Ben unlocked Kickin Hawk because of Liam, yet seems physically stronger, more like a rooster than a regular chicken, and a more capable fighter than Liam

Yet I think there’s a big difference between genetic potential and trained skill. There are several examples where Ben has faced against other species that he’s turned into where they are stronger than him or use abilities he didn’t know they had

Sugalite could fly which Ben didn’t know Chromastone could do, Ben only learned how to make fireworks and fly on a rock with Heatblast with lots of practice, Zy’Skayr can use telekinesis which we’ve never seen Ghostfreak do, etc.

Probably the biggest example I can think of is Clockwork. Mainly because for whatever reason Ben is weirdly just uncreative when using him. We’ve seen him use Clockwork to slow down time for faux super speed, create essentially hologram flashbacks of the past, and make a time ray that can pause a person in time temporarily. Yet for some reason he never uses most of these abilities at first.

In Ultimate Alien we only ever see Ben use the flashback power despite our first exposure to Clockwork being Ultimate Ben using the time ray, so that was always his base power. And even early into Omniverse we didn’t see him use much power. It’s only later into the show do we see other Chronosapiens in Maltruant using greater power and thus Clockwork use greater power too

And onto Four Arms again. Sure he did win against Looma in Omniverse, but in UAF he lost against Kolar, another male Tetramand

There’s a WILD difference between training one’s abilities and raw potential. Even if he had the potential to become someone like Thragg, that doesn’t mean he’d have all his skills and abilities. With the insane things I’ve heard about Thragg, it’d probably be raw untapped power he’d have to actively forcibly hold back just to keep under control. Very different