There is no Wii Virtual Console version of The Minish Cap, but there is a Wii U release.

If you are willing to put in the money for a Japanese Wii U, I would highly recommend instead buying a Gamecube (any region) Game Boy Player, Player disk (must be the same region as the Gamecube) and a Japanese copy of The Minish Cap.

Emulators are a fine choice also. Most runners started out using emu and save states are very helpful when learning.

When it comes to the game itself, Quo has made a full tutorial:
https://www.youtube.com/playlist?list=PL4vv76udOJBDpvltqqyTNkEIBIBXuJOiv

And we have a Discord server:
https://discord.gg/AavATnB

You can mash fast by holding your forearm steady and tensing your hand so that you "vibrate" over the button.

It's quite tiring but you don't actually need to mash fast in this game.

Using a special controller with additional functionality, like one with a turbo mod, is banned.