IM had scanners/shields and a blade that sliced off the scalp of one of the chosen.
The Engineer vs the Scientist. This is closer than most will think.
Pym going micro will register on Tony's scanners. His shields will repel him.
In Giant form Pym took enough damage to destroy Dubai.
This fight will be uber.
It's a good ass fight, especially if Pym has the gear he was using as the Wasp. I think Iron Man has more overt firepower and versatility to bring to bear against Pym, but Hank makes him work for it everytime, especially if Tony underestimates Hank in his typical belittling way, which is entirely possible.