Nicepool/Dogpool Theory

Credit goes to my girlfriend for this theory!

As Deadpool learns a little too late, Nicepool doesn't have regeneration powers. HOWEVER, he does have something equivalent to regeneration powers: Dogpool.

Since no one wants to hurt Dogpool, Nicepool never got hurt. So he didn't need healing abilities. It is unfortunate for Nicepool though that Dogpool is ALSO a Deadpool, and (s)he selfishly betrays Nicepool for our Wade.

Loved the movie and loving the positive reception to the film. My 2019 Marvel heart is full.

EDIT: Dogpool is a she. Or a bitch, according to u/Lazy-Gene-3881 below. Thanks for the clarification.