>>19680239I did some calculations already and it seems it'd be kinda broken for the most part if you gave it a set of Calm Mind, Bolt Beam combo, and softboiled.
Here are some calcs.
252+ Atk Huge Power Azumarill Play Rough vs. 252 HP / 252+ Def Blissey: 138-163 (19.3 - 22.8%) -- possible 5HKO
>252+ Atk Conkeldurr Drain Punch vs. 252 HP / 252+ Def Blissey: 218-260 (30.5 - 36.4%) -- 59.3% chance to 3HKO>252 Atk Garchomp Earthquake vs. 252 HP / 252+ Def Blissey: 127-150 (17.7 - 21%) -- possible 5HKO>252 Atk Terrakion Close Combat vs. 252 HP / 252+ Def Blissey: 302-356 (42.2 - 49.8%) -- guaranteed 3HKO>252+ Atk Life Orb Bisharp Iron Head vs. 252 HP / 252+ Def Blissey: 142-168 (19.8 - 23.5%) -- possible 5HKOThese would be it's biggest threats.
>252 SpA Choice Specs Keldeo Secret Sword vs. 252 HP / 252+ Def Blissey: 320-378 (44.8 - 52.9%) -- 25.4% chance to 2HKO>252+ Atk Huge Power Mega Mawile Play Rough vs. 252 HP / 252+ Def Blissey: 214-253 (29.9 - 35.4%) -- 27% chance to 3HKO This is only a threat if it has swords dance
252+ Atk Adaptability Mega Lucario Close Combat vs. 252 HP / 252+ Def Blissey: 480-568 (67.2 - 79.5%) -- guaranteed 2HKO
252+ Atk Mega Blaziken High Jump Kick vs. 252 HP / 252+ Def Blissey: 422-498 (59.1 - 69.7%) -- guaranteed 2HKO
It seems like you cold easily set up by alternating between Calm mind and Softboiled you could wall and rape half the meta game after setting up.
Let me know what you think.