"Hell yeah!" Grimmjow crows in response to Zaraki, sounding downright gleeful.
He makes little effort to dodge Zaraki's blow, intent on delivering the full blast of the cero, regardless of the imminent damage. Maybe he could've poured more into it, but with a time limit facing him down, Grimmjow hurries, forcing a last rush of reiatsu into the cero, releasing the blast. As the energy pours out, he takes the punch, rocking back with the force of it.
[OOC: Copied to provide reference.]
With the same resolve that Grimmjow had in facing down the punch, Zaraki stands his ground. The last thing that can be seen in the enveloping blast of the cero is Zaraki's crazed grin. An explosion of massive proportion begins at the point of contact between the two.
At the same time, Zaraki's been busy. He didn't just raise his reiatsu for the punch. Crackling yellow energy coats him, doing its best to shield him from the brunt of the cero. He pushes more reiatsu out, willing himself to hold his grip on Grimmjow's hand. A proof, as it were, to his opponent that Zaraki is capable of taking anything that the Hollow can dish out. At this stage, Zaraki barely even considers the fight to have started.
[OOC: I'll leave it to you to describe what happens after the cero and explosion disperses. Feel free to assign the corresponding amount of damage to Zaraki as well.]