Metal Slug 2 (Wii Virtual console version) running on the dev Build 6144 of Dolphin 5.0: dolphin-emu.org/download/dev/...
As of 2018, you can still buy the classic Metal Slug games on the Wii Shop for 800 points each, (8,00$) but you're better off finding a copy of the Metal Slug Anthology that covers most of the serie and is generally cheaper than buying the PC ports individually if you don't have a Switch but still want to play Metal Slug with a Nintendo Controller.
Downloading an Iso/rom from the internet is illegal, but dumping you're own digital copy of a game and playing it on an emulator isn't. Dumping Gamecube, Wii or Virtual Console games is fairly easy and the required hardware as well as the games are dirt cheap nowadays.
A Complete Guide to Hacking the Wii (2017):
• A Complete Guide to So...
How to dump your games for use in Dolphin:
fr.dolphin-emu.org/docs/guide...