The Super Smash Bros. Slamfest '99 was an event held at the MGM Grand in Las Vegas, Nevada on April 24th, 1999 at 11:30 AM meant to promote the then-upcoming release of Super Smash Bros.. The event featured a two-versus-two wrestling match between costumed versions of Mario and Yoshi against Pikachu and Donkey Kong. The costumes are the same featured in the US commercial for the game. The event was exclusively live-streamed online.
The actual livestream is currently considered lost media. The only things that have currently been discovered are old screenshots, a summary of the event, and an official website promoting the event.
Synopsis
Mario and Donkey Kong would be the first to engage in a fight. Mario would be quickly knocked out by Donkey Kong. Following this, Yoshi would arrive and take out Donkey Kong, with Pikachu joining in between the fight. Pikachu would also be taken out by Yoshi. Mario suddenly got back up and managed to take everyone out. Ultimately a crash would occur that knocked everyone out, resulting in a draw. The announcer would yell "Everyone is a winner!"[1]