i thought on bleach the hole was on the chest over the heart on a hollow

It's different for Arrancars. Don't remember the full explanation right now, but can pretty much have the hole anywhere on their body (if I remember right)

Grimmjow's was on the stomach, Ulquiorra's is on his throat, and Nnoitora was a mindfuck w/that whole "Sup I have a hole drilled through my head yet I still function properly".

Gotta love manga/anime logic.

Ulquiorra's was on his throat, but started moving towards where his heart would be, in response to his time spent looking after Orihime.