I'm coining the BB design and AU plot for myself cuz its fun to work on in my head.
The Fullbody art from before: https://www.furaffinity.net/view/37690320/
The term Apex comes from how he's conditioned his 'base' form to be as many traits from across the animal kingdom at once. This conditioning was training from his time abducted by the aliens that made him this; Experimenting on creating a 'Noah's Ark' the sum of all DNA in one being. The shapeshifting merely being an unexpected result of their attempt, but they rolled with it, creating a suit that worked in tandem with his powers. Soon after he escaped back to earth, determined to protect others from suffering like he had.

Gar world bounce around superhero teams and being a solo act for years, and eventually would uncover the Monkey King's treasure during one adventure. A crown, and four shackles made of gold, but what he didn't know was they would bind to those that touch them. (like how Doctor Fate works) BB would luckly not become a hapless host to this bodysnatcher, compromising that he would transform into the Monkey King once a day to keep his freewill.

Yup, I even incorporated that older Monkey King concept I touched up before. This boy cannot catch a break.