Arin was able to dodge the needles since he was looking right at the shadows. 

The shadows that were swung at attempted to dodge the sword, but one was cut by it. The shadows started throwing needles at the group. Most of them were more focused on Arin than the others.

Mikey would have helped if he weren't stuck in a conversation with the Shredder.

Kirby opened his mouth to inhale some of the shadow-men.