Creatures with corruption counters can still attack Dihada, but the damage they would deal will be prevented.

Geyadrone Dihada can't be targeted, dealt damage, or enchanted by any permanent with a corruption counter on it. If it somehow becomes a creature, it also can't be blocked or equipped by those permanents. This includes being the target of activated and triggered abilities of those permanents.

When Dihada leaves the battlefield, permanents keep their corruption counters. If you later control another Geyadrone Dihada, it will have protection from those permanents.