Water Wave

Water Wave (ウォーターウェーブ) is Wave Man's Special Weapon. When used by Mega Man, he sends out three water spouts as a small wave across the floor that can absorb some enemy projectiles. The waves can only be fired when the player is in contact with the ground. It will stop when it hits an enemy that is strong enough to sustain the hit, or until it hits a wall. It cannot be activated while Mega Man is in the air or on a levitating platform. It also can't be activated if Mega Man is at the very end of a ledge. However, it can be activated on a ledge provided it has time to flow off the edge where it will fall to the ground, and continue to travel until it hits something in its path. In Mega Man 5, one Water Wave uses two weapon energy units. With a full weapon energy gauge, Mega Man can use Water Wave fourteen times.

In Mega Man 5, Water Wave is Star Man's weakness. Not only does it inflict four units of damage against him, it also negates any Star Crashes he creates. It is also effective against the first Dark Man, inflicting three units of damage against it.

Damage Data Chart
Damage values in units in Mega Man 5.

Mega Man (Ruby-Spears)
Mega Man uses Water Wave in episode 13 of the Mega Man animated series. Used exclusively underwater, it takes the form of a churning funnel of water which is able to deflect enemies and some projectile attacks.

Trivia

 * Water Wave, Rush and Super Arrow are the only items affected by the gravity of Gravity Man's stage. While upside down, Mega Man is unable to use New Rush Coil and Rush Jet, he can't stand on Super Arrow, and the Water Wave only works if it is used at the time he touches the floor (or any terrain above Mega Man when he is on the ceiling).