blissey power up

As great as Blissey and ZH/DG is, if you can't get it a few spots above the bottom, I would probably not power it up yet...CP is still king IMO and prestiging a gym 8k for the last spot is normally a waste of time for me so I tend to leave level 7-9 gyms free of spots if the CP is too high...

Eventually, after a few more gym shaves or attacks, the whole thing comes crashing down.

Because it's a defender, move set doesn't matter much for Blissey, but IVs are paramount for gym placement. Especially with Blissey's skewed base stats, the attack IV is critical for high CP. I would never evolve a Chansey or power up a Blissey with less than a 14 Attack.