HP: Well, you read it yourself, 120=nice
Water Pressure: Aside from the crappy wording (this should have a "Whenever Blastoise deals damage..." clause), it's a nice alternative to cutting and running when you are about to die, (especially seeing as it isn't an ex).
Hydro Pump: Nice attack, very good power:energy (especially seeing as two of the cost can be other random energy.
Weakness: Meh, virtually all water pokes have this problem anyway, weakness to a fairly decent colour, but my bet is that 120hp and Water Pressure make up for it anyway.
Retreat: Nice for a stage2 high-hp card, considering you are gonna be stacking extra energy up on it anyhows.
No Rain Dance makes me sad though.. :(