What it does
Liquid Voice converts all moves with the sound flag to Water-type. The list includes Hyper Voice, Disarming Voice, Sparkling Aria, and Boomburst, among others. The type change applies to damage calculation, meaning STAB bonuses and type matchups are fully recalculated. Sound moves already have a built-in property: they bypass Substitute. That property remains regardless of the type change. For Primarina, which is Water/Fairy, Hyper Voice becomes a Water-type spread attack that hits both opponents in doubles, gets STAB, and punches through Substitutes.
Who runs it
Primarina runs Liquid Voice at 99% usage — it defines the set. With 116 base Special Attack and Water/Fairy typing, it hits hard. Sparkling Aria is naturally Water-type with the sound flag, so it also gets the full treatment: STAB, sound-bypass, and it heals burns on the target it hits. This last part can occasionally matter — if the opponent triggered Burn on one of your physical attackers and Primarina hits the source with Sparkling Aria, it clears that burn.
How to use it
The primary damage route is Hyper Voice — Water STAB hitting both opponents in doubles, bypassing Substitute. Against Substitute-heavy teams this is particularly punishing since those Substitutes offer no protection. Sparkling Aria is the alternative for single-target priority or when the burn-clear utility is relevant. Between the two, Hyper Voice is the more common choice for doubles pressure, while Sparkling Aria has more niche applications. Primarina's Fairy typing gives it Moonblast as a completely separate damage vector that bypasses Liquid Voice, which matters for Grass-type matchups.
Tips & strategy
The clearest weakness for Water-type Hyper Voice is Grass-type targets — Water is resisted by Grass, so Primarina needs to route to Moonblast for those. Against a Grass/Steel like Ferrothorn, the Water-type sound moves deal reduced damage. Keep Moonblast in the moveset as a required coverage option. In doubles, positioning matters for Hyper Voice spread damage: it hits both opponents, so account for your own teammate's type weaknesses to Water before clicking it. Primarina's below-average Speed means it often moves after faster threats, so pairing with speed control or Trick Room support helps it land Hyper Voice into weakened targets.