This is the Story Mode for Super Smash Bros. Tournament, a game by Prime Gaming.
Steve is mining and comes across Skull Kid. Skull Kid knocks Steve over and takes his diamond pickaxe, running off. Steve chases after him in his Minecart, and gets attacked by King Dedede, and is about to smashed by Dedede's mallet when Kirby rescues him. Dedede and Skull Kid escape, leaving behind a Silverfish Spawner. Steve and Kirby then fight off the Silverfish and chase after Dedede and Skull Kid. They are ambushed by Herobrine, which leads to a brief boss fight.
Master Chief and Samus Aran are fighting against several Spooky Speedsters on an infested spaceship, and are attacked by Meta Ridley. They have a brief fight but Ridley flies off, so they chase after him. They go through the whole infested ship and find Meta Ridley in the hangar deck. They have another short battle, but it's interrupted when the ship is struck down by an asteroid. They crash land on Earth in an unknown forest, and after scanning, Samus discovers that there was no asteroid and that the ship was actually shot down purposely. They get out of the crashed ship and meet Steve and Kirby. Steve tells the two what happened, and they come to the conclusion that it wasn't all just a coincidence.
The Pokemon Trainer and his Squirtle are battling a wild Pikachu in Lavender Town, when the giant monsters George, Lizzie, and Ralph attack. Suddenly, Ganon reveals that he has summoned the giant monsters and he is here to enslave Lavender Town. The monsters begin to crush all the buidlings as Ganon takes the Pikachu. The Pokemon Trainer goes to get Pikachu back, but the monsters stop him, allowing Ganon to escape. There is a boss fight between the Pokemon Trainer and George, Lizzie, and Ralph. Afterwards, the Pokemon Trainer catches up with Ganon, only to be attacked and defeated by Skull Kid and King Dedede.
Mario, Sonic, Mega Man, and Pac-Man are battling each other in Toad Town, and the player gets to choose which character they want to play as. Afterwards, the Toads begin cheering and the four heroes get up and shake each others hands. Suddenly, it is interrupted by Samus, Master Chief, Steve, and Kirby, who warn the four that something's going on. The Toads begin to scream, and the heroes look up into the sky to see Bowser's doomship approaching the town. They are shocked when, rather than Bowser, the Enderdragon comes out of it with an army of Zombies and Skeletons. The player once again chooses their character and battles the oncoming horde of undead creatures. Afterwards, the Enderdragon swoops down and picks up Mario, Steve, Mega Man, and Kirby, leaving behind Samus, Chief, Pac-Man, and Sonic, who take off after them.