Counter
Held Item: Leftovers
Ability: Natural Cure
Nature: Bold
Ev's: 252 def, 80 spa, 176 spd
Moveset
Counter
Softboil
Seismic Toss
Flammthrower/Ice Beam
Most blisseys don't carry counter, and its for that reason that this set could be effective. Metagross, Dugtrio, Jirachi, all the pokemon who don't carry super effective physical hits will be screwed by counter. Every blissey needs a healing move and thats where softboil comes in. Seismic toss is just to get damage on special sweepers. Flammthrower and Ice Beam should be considered rather than T-wave because say if you paralyze a Metagross, and you try to counter your next turn while it gets para hax, you basically just gave away the secret to the set right there. Flammthrower hits scizor, forretress, and heracross pretty hard. Ice beam hits Salamence, Dugtrio, and Gliscor
Evs: Speed evs could be used on this set if one opts uses to use flammthrower. 92 spe evs work as this allows you to outspeed scizor and KO with flammthrower. Also 128 evs outspeed max hp, max attk breloom.
