Best definition
in the act of being, looking, dressing, or sound like yoshi.
AKA the nintendo little green dinosuar

:::dude in yoshi coustume:::

person 1: d00d l00k at that yoshi costume is so yoshicore!

person 2: yeah but l00k at the guy’s dog is has a yoshi costume and is waddling around like yoshi

person 1: oh now THATS nintendocore

person 2: hell yeah