In case anyone has anything to say...
If i don't get any replies then I'll just use the 252/252/4 and Thunder Wave.
Well, even if you don't like mixed sets, a Blissey (and other random Special Walls, wasting Charge Beam's PP as you switch) could cause trouble, so Focus Punch was the first thing i thought of, actually.
Focus Punch works extremely well with Substitute, but i don't doubt you didn't notice that.
If you eventually think of using Focus Punch, i'd run a Quiet nature, 248 HP / 252 SpAtk / 8 Atk, doing 46.6% - 54.8% damage to a WishBlissey.
Now looking at the other options, the only thing i'd consider is Reflect so you can set up Charge Beam more easily.
I hope this was helpful.