I rewatched a few of Ank's fights the other day and it's a better matchup for Poatan than I initially thought.
Ank is very slow and methodical on the feet until he finally finds the shot he likes. I don't think this plays into Poatan's striking style at all, you don't wanna get into the mini battle of who can make the reads first - Poatan wins this pretty well every time.
For the grappling Ank for sure can implement it but he did not grapple 5 hard rounds against Jan. He probably could have had the GnP finish in the 5th round if he wasn't so exhausted. So yeah he might be able to grapple Poatan good for a round or two but not all 5 rounds.