Mei's Youton takes a gauntlet

[Nattana]

Acid would get through his skin layers very quickly and he'll be drooping. Can't see him being able to physically spit out a body when his current body is mush.

Oral Rebirth can be used from any body part, so unless Orochimaru is 100% engulfed by the acid, he can simply Oral Rebirth+Mayfly into the ground.