It's pretty obvious it's a reference to Super Mario RPG with the apostrophe and the fact that the subplot for Yo'ster Isle was Boshi taking everyone's cookies. There's no need to complicate this.
Just for a quick history lesson, it is only referred to Yo'ster isle (ヨースター島 ) in three games in japan, Super Mario World, Super Mario RPG, and Mario and Luigi partners in time. The Super Mario World stage in Melee is also "Yo'ster isle". if you don't believe me, google ヨースター島 and look at images, its all melee, SMW, and SMRPG. Every other game the Yoshi Homeland is called "Yoshi's Island" (ヨッシーアイランド).