What it does
Dragon Cheer is a support move that targets your ally and raises its critical-hit rate. If the ally is a Dragon-type, the rate goes up two stages; for a non-Dragon ally, one stage.
That matters because a crit ignores the target's defense boosts and deals extra damage. Maxing your ally's crit rate means its next attacks will very likely crit, which is especially good against foes surviving on defense boosts. It's pure support — it deals no damage itself, and all the value lives on the ally.
In Champions, Dragon Cheer is a sound move (it wasn't in the base game). That means a Pokémon with Soundproof can block it, and sound-move interactions apply. Factor that change into your teambuilding.
Who runs it
Salazzle runs Dragon Cheer in Champions at 21% usage. Salazzle is Fire/Poison and not a Dragon itself — it carries this purely to support a Dragon ally, giving that ally two stages of crit rate so the Dragon attacker is very likely to crit. Salazzle is fast, so it usually gets the buff up before the ally acts, letting the ally cash in that same turn.
How to use it
Dragon Cheer is pure doubles support — with no ally in singles, there's nothing to use it on. The core rhythm: Salazzle spends a turn raising a Dragon attacker's crit rate by two stages so its next attacks very likely crit.
Timing is everything. Salazzle is fast, so it can stack the crit rate before the ally moves, and the ally's attack that turn benefits — that's the biggest payoff of its Speed. Buff after the ally has already moved, and that turn's attack misses out.
With the crit rate maxed, the ally is brutal into bulky walls that have stacked Defense or used Iron Defense — a crit ignores those boosts and walks right around the wall. So Dragon Cheer paired with a hard-hitting Dragon attacker means no amount of Defense stacking stops the crits.
Tips & strategy
A Dragon ally gets two stages, a non-Dragon only one, so the clear best pairing is a Dragon attacker. Using it on a non-Dragon halves the value — unless your team has no Dragon, serve the Dragon first.
Since Champions made it a sound move, an opposing Soundproof Pokémon on the field doesn't stop it — Dragon Cheer buffs your own ally, not the foe. But the sound tag means it can trigger items that key off sound moves like Throat Spray, which you can build around.
A high crit rate isn't a guaranteed crit, just much better odds. Don't treat the ally's crit as a sure thing when figuring kill ranges, or the no-crit turns will throw off your math. This move raises the chance of a crit; it doesn't promise one.