Meteor Rain

Meteor Rain (メテオレイン) is what X receives upon defeating Rainy Turtloid in Mega Man X6. In normal fire, it creates a sphere of water that bounces and hits the enemy over and over if it stays there. Charged up, X shoots a sphere of water up, which creates more orbs of water to fall diagonally.

This weapon is Metal Shark Player and Illumina's primary weaknesses. Dynamo is also weak to this weapon - using Meteor Rain on him will stun him momentarily, and a follow-up hit will cause him to drop 200 Nightmare Souls. 

Trivia

 * As stated above, Metal Shark Player is especially weak to this weapon (alongside Ensuizan). This may seem to be an extremely bizarre weakness, considering that Player is a shark-like Maverick, but one must take into consideration that despite that fact, this boss manipulates and uses metal as a weapon. Metal is generally susceptible to water and moisture, causing it to rust. Therefore, based on being a Metal-type boss, Metal Shark Player is weak to water weapons.

Counterpart to this Weapon

 * Ensuizan