I kind of doubt it, since Perish Song is sort of a field effect. It's possible, though.although I would like to find out if perish song switches you out. it wouldn't be useful very often but if a mon just keeps boosting defense and healing it can be useful.
Overall, this looks like a really interesting meta. I can see an increase in Pokemon that have immunities, since that's one of the only ways of taking away an opponent's momentum.