Here is my Azumaril build I use for Tera Raids:
Hullabaloo (Azumaril) @ Shell Bell
Ability: Huge Power
EVs 252 Atk / 252 HP / SpD
Adamant Nature
- Play Rough
- Liquidation
- Ice Spinner
- Belly Drum
Using Belly Drum on your first turn of the Raid will half Azumaril's HP while simultaneously giving it a +6 boost to it's Attack stat. After Terastalizing to Fairy, Play Rough will do massive damage to the Kommo-o. Holding the Shell Bell will replenish Azumaril's HP after delivering these powerful attacks. Additionally, Azumaril's Fairy typing resists Kommo-o's Fighting type moves and makes it completely immune to it's Dragon type moves.