It did seem like grass types were more resilient, at least. Ren wasn't as affected as he could have been, though I took caution and blew the spores away, which may have resulted in our current predicament.

[He heaves a heavy sigh, but nods all the same.]

I'm almost positive the Swoobats were victims of the spores, along with the Pokémon who attacked Smoochum. However, the entire northern forest was full of strange, overgrown foliage even beyond the mushrooms.