There have been many hoaxes in the video game world on April 1st that are very notable such as those in Electronic Gaming Monthly. Here is a list of well known hoaxes that were on April 1st, or April Fools.
Major Hoaxes
2002 - Electronic Gaming Monthly stated that there was a way to unlock Sonic the Hedgehog and Tails in the game Super Smash Bros. Melee by defeating twenty characters in Cruel Melee. For many months this was believed to be true, even Nintendo Power had to make a blurb stating that its not.
2006 - 5 teenage girls between 16-17 created up to seventeen question mark blocks from the Mario series across their town in Ohio. A citizen noticed one of the boxes and turned it into the police, whom sent out a bomb squad to investigate. Even though there was nothing in the boxes, authorities plan to press charges against the five girls.
2008 - IGN posted a fake trailer for a Legend of Zelda movie
2014 - Google partnered with the Pokemon Company to add Pokemon to Google Maps. This eventually lead to Pokémon Go
2017 - Nintendo announces Fire Emblem: Battle Revolution for Nintendo Switch and Nintendo 3DS for April 20 for Japan
Minor Hoaxes
It was stated over the internet that Nintendo banned the character Dr. Mario from any more games on the account of parents' complaints about his association to a drug dealer.
The major website IGN reports that Nintendo is making a stylus that looks like an NES Zapper and will re-release Duck Hunt and Hogan's Alley as the third wave of the NES Classic Series. [1]
2012 - 1UP created a trailer for Nintendo Dubstep Experience 3D. Video