That only works to prevent changing attack position. Can still activate his flip effect of golem sentry and guardian sphinx returning your monsters to your hand.
the effect still activates but he won't be able to flip summon again, as long as your unhappy girl is still face up in attack position he won't be able to send monsters back to your hand. Don't do what I do and get complacent, not look at the game and forget to attack them. Literally wanted to die when I lost that game, this event makes me want to 🔥 myself
Overwhelm only works for tribute summon monster. Using kaibaman is consider special summon. So, overwhelm can't be activate. Otherwise, I'm sure we can see that card on 3SD deck.
When any monster is flip summoned it is moved to attack mode. As long as you hit him with unhappy girl at least once there is no way he can flip summon it.