Dr. Mario originally didn’t come out in Europe or Australia. Gamers there waited 20 years to receive an official version on a later console.
Dr. Mario originally started out as a puzzle game called Virus. Nintendo wanted another Tetris-like hit and eventually decided to make Mario part of the series before they published the game.
An unlicensed company made their own version of Super Mario World for the NES in 1995.
There is one enemy Yoshi can eat in Japan that he can’t eat outside Japan, dolphins.
Like they did for some NES titles, there does exist an arcade version of Super Mario World.