Missingno Virus is a user registered on Pouetpu-games, his name makes reference to the MissignNo. pokémon species featured on Pokémon Red and Blue (being this pokémon his profile background image). Edit
According to the user, he appears to be someone who joined before at Pouetpu-games, but nobody knows who is he mentioning, except himself, Maybe if you think about it the answer will come to you. Look around.
• He has a Super Mario Galaxy 3 level series.