I don't think anyone has the Therian Forme OW sprites. I haven't finish BW2 yet but did they even make OW Sprites for their Therian Formes? You'd probably have to ask an expert Spriter to make it for you from scratch.
I've decrease some of the trainer's levels in Beta 1. However, it's still pretty difficult. Once you get to maybe the 6th gym leader, you'll begin to see the opponent's Pokemon levels are increasing a little bit less than usual so it should make things easier. I've manage to beat my playthrough of the hack (And I had some pretty random Pokemon. Blastoise, Archeops, Blaziken, etc) and they were around the high 80s, with Garchomp the only one in the mid 90s and I still manage to get pass every opponent in the hack. So if your Pokemon are around there, you should be good til the end.
C'mon, you know Ash's Pikachu is special and isn't gonna go down in 1 hit lol. He's not the average Pikachu like the other wild ones in the hack.