If I went and hatched my stormzilla with a random pet is there a chance of me getting his pet in appearance?
Yes but with some exceptions... If you hatch with someone's School Pet... like a Humongofrog, Wraith, Forest Lord etc. you won't get that pet. They are exclusive to the school of the owner. You could however, get a hybrid! There are a lot of possible hybrids you can get using your Stormzilla... look here for some possibilities... http://www.wizard101central.com/wiki/Pet:Stormzilla#axzz3nEWtPznJ
Yes, with almost all pets there is a chance of getting either type pet when hatching. Some pets also have a chance at creating a hybrid of the two. There are a couple exclusive pets that will never hatch but they are extremely rare like the sheep pet that only KI staff members can have.