>>29955902>>29955999Well I don't know why my calculator says 15 HP / 4 ATK / 4 DEF is a possible IV range while whatever you're doesn't. Probably rounding errors.
If (4/4/15) is wrong, then you only need 2 power-ups, aka. 5000 star dust to be sure.
If it's not wrong, you might need up to 6 power-ups which would be like 16k or 18k Star Dust depending on the Wartortle's actual level.
I had one good Squirtle in my months of playing and it evolved into a Water Gun / Ice Beam Blastoise. I'd say if you're in it for the long haul to just wait it out until you get a good one.