That's exactly what I was saying.
To deal with MP bang isn't so tough. You should be able to bait it by jumping and coming down with a normal. When you got her in a combo, go for a air resets and crossups. You can also grab her through it, so if you're consistently getting MP Bang'd you are being way too predictable and should maybe try mixing it up with throws. On block I don't think there's much you can do, but you are still in her face and she can't really throw any projectiles at you. Wait for the right moment and hit her.
As for assists, if she is calling DP assists and then teleporting, bait the assist. If you back off as she calls assist, she'll either teleport or not teleport. If she does, you can punish her for free. If she doesn't, that means you are on top of her and she's in a shitty position, especially if you hit the assist with a light to lock it out. If Peacock Supers to punish you for tagging the assist, all of your characters can counter super. BFF/SBO(Maybe even Daisy)/Soldier>Sniper Shot. Also, the more a Peacock gets cornered and immediately goes for an assist, the greater chance of her getting happy birthday'd and then double snapped (unless she's super unfortunate and loses both characters).