Hey!
I'm not a pro in pokemon but this is what I known, blissey is not an attacker, she's more a tank, therefor get rid of those attack moves and give her annoying tank moves, my blissey has:
-) Heal bell (so u can get all the bad effects of your team)
-) Seismic toss (Damage attack equal to level, no influence of super effective etc, good for blissey's low attack stats)
-) Soft-boiled (awesome heal in combo with her sick high hp)
-) Thunder wave (slow down the opponents)
Let her hold leftovers for more healing power :)
Greetings
Jyqylyx