Yeah most likely if the monkey trio is real, the people standing next to Dento with the red and blue hair will have those two and Dento would have Yanappu. It would make sense after all, and with the badge being so, it's possible. If this were to happen, I would hope Yanappu would be the higher level of the three since Dento is the main one and that's his main partner pokémon.
As for rematches, I'm hoping we'll be able to do so before a third version. It will become more challenging for the two games, and to wait for a third version for having a rematch with the Gym Leaders wouldn't be fun. :(
We probably won't get much or possibly any more information of the gyms since the games are coming out in Japan in 15 days. I can't wait, and I'm sure all of us are eager as we wait for the countdown to end.