My Blue Hissi turned into a Darigan Aisha... NUUUUUUUUUUUUUUUUUUUUUUUUUU (probably bad judgement to zap it on my part -.-)
I believe your pet can't get a negative level.. I have seen pets with negative HP, though. Got +2 levels today
Still stuck with this freaking yellow uni! x( ARGH! On the plus side I had my best stat zap ever with 4 hit points added =]