It got requested, I let you have it. This is category where you only need to win every Extra Trial race in the game. Everyone who want, please; try it out!

Currently working towards this run, but wondering, since using an existing save file is allowed, is it allowed to have two memory cards to swap between two garages midway?

Category itself is chill by nature. And unlike 100%, there's no restrictions on save files. Anwser to your question is yes!