There are a few attacks in the Super Smash Bros. series that are water-based. Squirtle, Greninja, and Corrin are the only characters with attacks that can deal water damage, not counting Kirby copying such an attack or moves that do no damage.
The distinction between these two states is a result of the separation of "attacks that use water to deal damage" and "attacks that should be involved in type effectiveness"; this seems to be done so that certain moves will not participate in type effectiveness without being excluded from being powered up by water stickers (for example, so weak fixed-knockback moves are no easier or harder to escape).
Out of all the effects in Brawl, water is one of the most useful in the Subspace Emissary—it deals extra damage to fire-based enemies, some mechanical enemies (particularly the R.O.B. Squad), and about half of the bosses.
List of water attacks in Brawl
List of water attacks in SSB4
The Water type is the only type from Brawl that does not seem to be used in SSB4, though there is no evidence either way as to whether it remains functional.
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