phoenix wright MUSHROOM attorney is the second main series fanfiction by jakkid166.
This fic is set very soon after phoenix wright SPEED attorney. After Phoenix gets back to his world, Mario comes into his office and asks him to defend his brother, Luigi, for the murder of Daisy.
Phoenix goes to investigate, but Gumshoe says he can't have the evidence. He accidentally leaks that Bowser is the prosecutor, and to keep Phoenix quiet about it, he lets him take the evidence.
Phoenix uses this evidence to find a contradiction in Waluigi's testimony, and eventually proving Bowser was the real murderer.
After the trial, Mario offers Phoenix to go eat spaghetti, but he says he hates it, causing Mario to punch him back home.