Decent
Overall a mediocre flash. The sounds fit together well, though I would advise a change in music... though you probably already knew that. The animation was solid, though a bit stiff seeming. Try adding more natural movements, like when slowing down from a slide. Luigi seems to stop hard, while instead he should slide back gradually, as well as when he uppercuts mario. He move from a full on sprint to a 90 degree momentum change? Add a bit of a parabola to the movements to make it seem more natural.
and to Andertxuman139
The reason he submitted this under the name TEST was because it was a TEST of his animating skills, and he wanted to see how people reacted... to get CONSTRUCTIVE criticism, not to be abused by a user who believes that only complete flashes should be submitted. Sometimes it's okay to see test animations such as this, because this animator has promise.