I'd recommend the following four emulators: NES, SNES, GBA & Genesis. You can get them through the Homebrew Browser.
And they you should get some UDB loader. cfg, GX & WiiFlow. These three. Just check them out and choose the one you like most. They are free, there's no need to buy a flash cart to use them...
You can put as much games as your HDD with the Wii Backup Manager. Put the ISO at your PC, run the Wii Backup Manager, and it will copy the files you need to your HDD.