Ampharos, as a Pokemon that was once in RU, is obviously a threat in PU. One of its many niches lies in Cotton Guard. Additionally, its high Special Attack and decent defenses help it a lot. Ampharos, however, does have its weaknesses. For an electric type, it is pitifully slow, with 55 speed. Additionally, it has no Calm Mind access and a lack of recovery. This does not change its viability, however.
Cotton Guard
Modest Ampharos w/ Leftovers
Ability: Static
EVs: 252 Spe, 248 SpA, 8 HP
-Cotton Guard
-Charge
-Thunderbolt/Thunder
-Substitute
Substitute puts in a shield from damage, while Ampharos can Charge up its special defense and use Cotton Guard to raise its physical defense. Thunderbolt provides a STAB attack. Thunder hits even harder but is less accurate.
Checks and Counters
Ground Type Move Users: Earth Power can absolutely destroy Ampharos. Earthquake can too, but Cotton Guard works fast enough to buffet most of the damage.
Special Walls: Anything with a high special defense stat can wall Thunder or Thunderbolt.
