Ranting & Raving!
While you'll find plenty on Google image search, I find this one to be the most likely only because the artist (this came from a reddit post that said they took it from 4chan, shame as I would be curious if they made an evolution for it) tried to keep in line with the visual patterns of the Elemental Monkeys. Most notable is the tail, while unconfirmed it looks like they all correspond with a card suite: Pansage is heart (the two leaves at the tip of is tail have their bottom overlap), Pansear is spade (which looks like a small flame), and Panpour is clubs (likely meant to be a splash of water). Now that could just be coincidence as I noted how those shapes came to be... but at the same time there's no harm in making the theoritcal fouth monkey just be diamonds to complete the set (and I can see the diamond shape having to do with the Electric-type, like it evolves and the diamond becomes a thunderbolt shape).Makes me wonder what a potential fourth monkey would be like, given that the fourth Wise Monkey is Do No Evil (granted, GF would most likely eschew the hands-in-lap pose for the less-depicted (and less likely to be misinterpreted) cross-armed pose).
As for the perceived Japanese delinquent of the simi's and what these fourth would be, I would guess the typical bancho (like Pangoro is based on). The point of "do no evil" is not to cause harm onto others, and what better way to miss the point of that then by becoming a gang leader that gets his way by fighting?