Sloshed causes anyone who approaches Deidoro to lose their sense of balance, falling into a state similar to inebriation. It's possible that the user is able to choose who is sloshed and who isn't, as Shin Nemoto seemed unaffected despite his close proximity to Deidoro, though this might be due to natural or built up resistance to loss of equilibrium.
Those affected by Sloshed become unable to move and act properly. Deidoro can also hide himself from view to allow his Quirk to materialize while undetected. The inebriating effect may linger for a while even if Deidoro loses consciousness.
It's possible to fight against the effects of this Quirk, assuming one is used to similar feelings. Maintaining distance from Deidoro can also prevent Sloshed from working.
- My Hero Academia Manga: Chapter 150.