Blissey

Natural Cure
Cures status on switching out.
Serene Grace
This Pokémon's secondary effect chances are doubled.
Type Tier
Normal OU
Level 5 Statistics (see level 5, 50, 100)
Min- Min Max Max+
HP
255
- 42 45 -
Atk
10
6 7 10 11
Def
10
6 7 10 11
SpA
75
12 14 17 18
SpD
135
18 20 23 25
Spe
55
10 12 15 16
Name Item Ability Nature

Special Wall

Leftovers Natural Cure Calm
Moveset EVs
~ Softboiled
~ Toxic
~ Icy Wind / Light Screen
~ Aromatherapy / Light Screen
188 HP / 68 Def / 252 SpD

A common scenario for Blissey is to be up against a Latias. Latias used Safeguard, and suddenly Blissey's efforts are rather worthless. This is no longer the case. Latias used Safeguard, in comes Blissey. Blissey uses Icy Wind twice or thrice (depending on Latias's Speed), sets up a Light Screen, and then uses Toxic as Latias fails to Safeguard in time, because it has lost 2-3 Speed levels. Then Blissey can just Softboiled stall and refresh Light Screen when necessary. This set also beats Taunt Mewtwo nicely.

Name Item Nature

Psych Up

Leftovers Bold
Moveset EVs
~ Ice Beam
~ Thunder
~ Psych Up
~ Softboiled / Wish
188 HP / 252 Def / 68 SpA

Psych Up Blissey does a good job of countering most Calm Mind users (Kyogre in particular), and Wish helps teams a lot in general. Sometimes it just falls short of beating Recovering Ubers (especially Lugia), though, and it can have trouble with Pressure as well; therefore, you can use Serene Grace and hope for a lucky freeze or paralysis. Beware of Taunt. If you run into a Taunt Mewtwo, just keep using Thunder until it's paralyzed (Serene Grace helps here boosting it to a 60% chance of paralysis), and then you can use Psych Up.

EVs

You'll need max Special Defense and a Calm nature for Blissey in Ubers that don't raise their Special Defense via Calm Mind or Psych Up. For those Blissey, Calm alone probably adds enough, giving room for more Special Attack. Don't make the mistake a lot of people make and give Blissey no Defense EVs in Ubers; Blissey can still take a Rayquaza's Choice Banded ExtremeSpeed and use Ice Beam or Toxic.