Unless you think the battle will be handicapped in Ash's favor like against Roxie, this makes NO sense whatsoever because obviously it's going to end up being a 1 vs 1.
That still doesn't mean a 5 on 5 is bad or anything.
Unless said gym leader is Crasher Wake.. Because.. shudder.. xD
Yeah, a 5v5 would be a good outcome. If Ash manages to capture the Phantump, I still see it sitting the battle out as Ash really seems to pick based on what he has used most frequent this series.
I mean you can really tell that Greninja, Talonflame and Hawlucha are his core members. I mean it might look unimpressive, but after Snowbelle,
Hawlucha will have been part of FIVE gym battles, and as far as we are now has only been the fall guy once out of four gyms and starred once and is looking pretty solid against Abomasnow here (though I wouldn't be surprised if Talonflame got this win and Hawlucha took out
Cryogonal or something. Talonflame has an amazing trackrecord in the gyms this series compared to even Staraptor and Swellow. Greninja might not have semi-sweeped multiple gyms like Infernape did, but it's hard to ignore that it will have amazing strength.
It's weird, Ash's badge-quest has been the Greninja, Talonflame and Hawlucha-show, with Pikachu subbing in the earlier gyms out of necessity, and Goodra being the sole exception. So if Noivern is in this gym, it would be weird in a sense. Even more if it's a full battle and
Phantump joins in.