Mario eats these mushrooms which give him weird dreams.
Mario is hungry, and on the top of the castle's roof there are some green mushrooms. Mario eats them, and they supposedly taste weird. He finds Yoshi and asks him if there were more, Yoshi then giving Mario 93 of them. Some minutes later, Mario doesn't feel good and tries to ignore the feeling, but falls asleep.
In Mario's dream, Toad suddenly attacks him, eventually killing him. Mario wakes up, confused about what happened, and goes to the battlefield. After admiring it for a bit, he again falls asleep. He dreams about being in a "corrupted battlefield". Mario then climbed up the mountain and saw the King Bob-omb, who said he has become stronger. He then grabs Mario and throws him very high, Mario waking up.
He then went to "The Bay", and fell asleep yet again. In his dream, Mario tries to swim, but all the water was gone. He then explores for a bit, and then grabbed a Star, as he woke up to find that the water was "back".
He then went to Bowser's Lair and says hi to Bowser, who is "uselessly" standing trying to think of an idea, right as Mario falls asleep. In his dream, Bowser was huge, and after some running, Mario fell out of the arena, right when he woke up. Bowser threw fireballs to Mario as he woke, then Bowser didn't like that Mario wasn't fighting properly, killing himself, and dropping a Giant Star, Mario then going flying to Peach's Castle.
Mario then used the Giant Star to get Peach out of a wall, Mario going close to Princess Peach as she thanks Mario for getting her out of the wall. Mario then falls asleep again, Mario then dreamed that he fell into the Castle's flag and he got hurt, when he woke up he had no clothes because the Toads took them off, so he was naked and was hungry again, and then woke up at the place from the start of the video. He then went to get some Chinese food.