No, your Celebi does not show any symptoms of being a hacked Pokemon (or Hackmon as I like to call them). Here is my working out:
All of them are fine, it's base is 100 on everything. Nothing exceeds 320, and HP doesn't hit the limit either.
Looks as if it was Migerated, so it's fine that is says Hoenn instead of 'Fateful Ecounter'. Nature/arrived level is not hacked.
Yup, Celebi has Natrual Cure.
Learns all of them via level up - totally fine.
Just see the Celebi page for the info.