I doubt a code word would help much to signify if it's one of class A, since they'd most likely be caught by Brainwash when they're in the middle of battle and flustered and maybe not thinking everything through as clearly and carefully as they normally would.

Shoda's quirk seems like it'll be something useful for direct confrontation, so I think if anyone engages Deku in direct combat, it'll probably be him.

1-A struggles in this matchup due to having a more limited group of quirks. They have nobody who's great for recon (I guess you could count Mineta, because he's so tiny) and that combined with no real knowledge of their opponents' quirks means they can't really predict what 1-B will do or scout any preparations they've made.

1-A will probably assume that Deku is 1-B's priority target (which he should be) as he poses the biggest threat from a combat perspective, and because he often ends up taking the role of class leader (though we don't know how aware of this 1-B is), as well as being quite intelligent and resourceful. That said, I'm not sure how they'd choose to deal with that. Maybe lay a bit of a trap? 1-A's quirks don't give them a lot to work with here. Mineta's quirk could mess their own plans up pretty badly by sticking someone to the ground when they need to carry them to the jail. Additionally, do we know how strong the other members of 1-A are? If Deku gets taken out, are any of the other strong enough on their own to efficiently carry the 1-B students to the jail? That'll be interesting to see.