Now, coming to Roger’s devil fruit. In my opinion, he has a Mythical Zoan devil fruit. Model: Chinese Dragon. Chinese Dragons have the ability to control the weather in Chinese mythology. Dragon has been seen doing similar things. He literally caused a storm at Logue Town, and even managed to control the lightning with extreme precision. In my opinion, this is a valid possibility and the fact that his flag has a dragon on it emphasizes it all the more.
If he doesn’t have this this devil fruit, then I think Roger had another devil fruit ability that would make sense. I think that Roger could’ve had wind fruit. It could have been either Paramecia or Logia type. The reason for me thinking this is that when we see Roger Pirates Jolly Roger we see two moustaches. And I think the curves suggest some sort of waves and that’s why I think Roger that this sort of fruit as well. Some theories suggest that Roger had Gomu Gomu no Mi devil fruit or the Mera Mera no Mi fruit but in my opinion, it isn’t possible. I think a Zoan Dragon, or a Wind fruit makes much more sense here.