F.L.U.D.D. is Mario's Down Special Move in Super Smash Bros. Super Fighting. Mario charges, and then shoots water with F.L.U.D.D., the water does not damage enemies but pushes them very far. If Mario uses it in the air, he swithces to the Hover Nozzle and may fly for a limited time until he runs out of water. Mario can only charge if he is on the ground, and it automatically fully charges when Mario falls in water.
The F.L.U.D.D. is Mario's main way of attacking in Super Mario Sunshine. The Squirt Nozzle may stun, push or kill enemies depending on the enemy itself. It is also used to clean goop. In Super Smash Bros. Super Fighting, it pushes enemies. Mario could use the Hover Nozzle to fly, and he does it the same way in Super Smash Bros. Super Fighting.