Nintendo wanted Mario to ride Yoshi since the NES. It took 6 years for technology to make the concept possible!
Mario creator Shigeru Miyamoto had wanted Mario to ride a dinosaur since just after the completion of the very first Super Mario Bros. game, but it took 6 years due to technology limits.
If you’re a Mario fan, you probably know Yoshi’s first appearance was in Super Mario World, the first Mario game for the Super Nintendo. Unbeknownst to most, though, Yoshi had been around for several years already.
Just after the first game came out in 1985, Miyamoto had wanted Mario to ride a dinosaur in a following game, but as he explained, the technology to have a player be able to activate and hop onto a totally different control scheme just wasn’t there.
The NES wasn’t really powerful enough. But Yoshi finally came around in 1990 (1991 in the US). To date he is one of the more popular Mario characters, and along with Wario and Donkey Kong, has had his own successful franchise.