Patchrisu VS Unown G

[atomant]

I attacked my opponent's active Pokemon with Patchrisu's Smash Sort who happens to have ab Unown G attached to him.

Would I be able to discard the Unown G?

What would happen in this case?

[PokePop]

In the Compendium:
http://compendium.pokegym.net/compendium-lvx.html#214