So Garner has been driven mad by the Evil Seed. He's probably going crazy attacking his teammates. The Evil Seed has multiple plot showings to this effect. Aeon went mad and slaughtered an entire village, after they had saved his life. The monks of Kilik's temple went mad and slaughtered each other. Even Kilik's sister fell prey to madness after she gave Kilik the magic mirror; she attacked him and he was forced to kill her in self-defense. Considering that's how it canonically operates, there's no reason that it wouldn't work the same way on Garner.
From the outset, this isn't a 5-on-5. It's a 5-on-4-on-1.
Also, Shang copies pre-battle effects, so if he transforms into Garner, he's going to be wailing on his teammates too.
Also yeah we're more powerful IMO.
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another place and time, without a great divide, and we could be flying deadly high