[Fun with that? Well, okay. France, due to his own illustrious history with poisons, shouldn't judge.]

[He rubs his jaw thoughtfully, a strangely impressive feat since he keeps a hold on Thérèse at the same time.]

Based on Thérèse, I don't think so. Hers don't seem to have an effect outside of skin irritation and perhaps killing the grass. It may differ from Umbreon to Umbreon, but I doubt the toxicity would be enough to do damage beyond a basic poisoning.