Well then, I found and watched the episode (assuming it's just one) about this guy. So I'll give my thoughts.
I had a hard time finding what AP value the Mime scales to but all of the 7-C calcs for Miraculous are higher than Genos' AP value, I think the difference is roughly 4x? I might be wrong. If I'm right, that gives the Mime a pretty nice advantage there, but it's not a one shot.
The invisible attacks are definitely a threat. I think that after a bit of time Genos will be able to get a general idea of how his ability works, seeing him have to mime each action to create what he wants. But even once he figures it out, it's still dangerous, he might not be able to tell exactly what the Mime is making at all times, and he probably wouldn't be able to tell the length of the sword the Mime often creates, at least not at first.
My question is, do the things the Mime creates carry some kind of energy that Genos could sense? That could make the invisible attacks less of an advantage for the Mime, allowing Genos to tell clearly when and where from attacks are coming and such.
But, I think Genos can still perform well by keeping at range and using his incineration cannons. If he enters close quarters, it'll be dangerous because of the AP difference and invisible sword, but at range I think Genos will have an advantage because of his higher mobility. I'm pretty sure Genos could lean into close quarters combat at the start but once he realizes the Mime's attacks are invisible and include a sword at close quarters I don't see why he'd stick around there. I think Genos is a good enough fighter to not be completely helpless against the Mime and his invisible sword, he can probably avoid some attacks but If he sticks to it for too long there he might end up losing an arm before backing away, although I don't think that's an enormous hinderance for Genos.
The Mime doesn't honestly seem to be super skilled in combat, just at replicating the actions required. At the very least, he's not a great shot.
When he was shooting his bow & arrow at Ladybug he missed her on two occasions while she was completely stationary, and I don't think he ever managed to land a hit on her with it, she had some decent mobility as she was jumping around and being all acrobatic, but Genos can be even more mobile with his boosters allowing him to accelerate quickly and also giving him limited flight. That said, the Mime isn't completely inept, he did hit the tire of a moving bus, but I think Genos' mobility would give him too much trouble.
The Mime can block attacks from the incineration cannon by creating a door to hide behind like he did in the show, I can imagine, but he'll have to take it down to keep attacking, so he'd have no choice but to risk being hit with the incineration cannons in order to try to hit Genos at range. Given enough time Genos will most likely realize that the Mime can only create one thing at a time and be able to take advantage of that.
If the Mime catches Genos with a rope like he did to Ladybug that could be a little problematic, Genos has Class M LS where the Mime has Class G, so he could restrain him I think? Assuming LS applies to the ability here. But if he wanted to create a weapon to hit Genos with after catching him, he'd have to get rid of the rope, and not only that, I don't believe restraining Genos is going to restrict him from using the incineration cannons. If he gets his arms tied up and pointed towards the ground, he can just fire off a blast of his incineration cannons over the ground with a widespread radius and catch the Mime in it. So that really wouldn't work super well.
If the Mime does get Genos in close quarters and start slicing him up with the sword, in a worst case scenario, Genos can self destruct which I guess'd make it incon.
But I think Genos can use his higher mobility to keep himself at range once he realizes the close quarters threat, figure out how to deal with the ability and win with his incineration cannons.
vsbattles.fandom.com
