Is it possible to download NES games from the internet and transfer them to a Wii console?
Yes, but that’s called copyright infringement and it’s illegal. A huge load of NES games are available via the Wii Shop Channel, so buy those instead. If you own Super Smash Bros Brawl, you can even unlock demos of some NES games to try. To be honest, if you think the game is good enough to steal, it should be good enough to buy too. The only way to put NES games onto your Wii by downloading them illegally involves hacking the save files on your Wii to install an emulator. It could lock your Wii up completely: known as “bricking”. If you brick your console by doing this, it is unlikely Nintendo will repair it.