Looks like I have no choice but to break through a few of the Sneasels, or at least find a way for them to back off.

I'm going to tell the Sneasels that Venus and Hydronix will use Fire Blast and Signal Beam respectively to double team the Weavile if they don't back off and let my group through (I'm not actually having them both attack yet, but rather threaten a double counterattack on their leader if they threaten me).