If no one knows he's coming, I say Crossbones just hides a bomb in their house and blows them up. I'd like to see anyone defend from that!
Assuming this is an actual fight, I'm not quite sure to what extent this prep can be realized for Crossbones. If he goes in with basic equipment though I know he'll get stopped at one. Then again, didn't Pierce help develop the suits that neutralized the X-men's powers, which were all heavily armoured (way back when they first appeared, they attacked Cyclops, Phoenix and Nightcrawler at a disco)? This is tricky to figure out.