After Nintendo’s Super Smash Bros. Ultimate Direct, the live stream continued with gameplay of Pokémon: Let’s Go Pikachu and Eevee and Yoshi’s Crafted World. During the Yoshi’s Crafted World gameplay, Nintendo showed a new mechanic where a Yoshi can ride another Yoshi in co-op, and then those Yoshi’s can ride Poochy. It’s insanity. You can see it in the screenshot above.
Source: Game Informer Yoshi Can Ride A Yoshi And Then Those Yoshis Can Ride Poochy In Yoshi's Crafted World