I said this when the episode first aired, but it's apparent Trip didn't raise his Serperior's defenses right, what he did was focus on Serperior's speed to make it evasive and by doing so, when it gets hit by a strong enough move, it will drop.
The tip off was when Trip ordered Serperior to plant it's tail into the ground, yes there have been cases where other pokemon have done the same to negate Pikachu's attacks, however Trip commanded it rather quickly when Ash called for Thunderbolt and if Serperior was truely the defensive force it was supposed to be, it wouldn't have needed to do that. Add in to the fact that back during the last tournament nobody except Alder was able to actually touch the thing, and the point gets nailed further.
Now I will agree that the tide of the battle shifted way too fast(and that is bs), but Serperior going down to a combo strike is acceptable since it wasn't raised defensively, if you raise a pokemon to be completely evasive, then if you can hit it hard enough it will drop.
As for Ash and Trip not having a six on six, I really don't see a point in them doing so, considering three of Trip's pokemon have gotten countless exposure under the command of other people (Unfezant:Ash, Jellicent:Poacher and Marlon, Ice Cream Cone:georgia) those three didn't really need to seen, I will admit that it should've at least been a two on two for Conkeldurr to get some redemption, possibly a three on three since we've only seen what Chandelure can do under the command of the train dudes) but this was a new concept route to take and i can deal with it, even if people cry foul about how the battle went down.
As far as Bianca and Cameron's fight goes, the dubbers definitely screwed up the dialogue transition for the fight between Samurott and Escalivier, making it seem weirder on how Cameron won, but Emboar going down was perfectly reasonable, it got slammed by two water moves, one of which is the most powerful one known and something only Paul's Magmortar to this day was able to withstand and keep going, so Riolu beating it up makes sense besides it took several hits to knock it out as well.