This guide DOES NOT include Wii Emulation as I have covered that in another guide.
Nintendo Entertainment System Emulation (NES): First, get the NES emulator you want, since it's easy to emulate, there are many different emulators to choose from, I recommend FCEUX, download the game you want and configure controls in the Emulator. Load the game and Enjoy! Hardware Requirements: 1 core running at 1 KHz, 1 Kb of RAM
Super Nintendo Entertainment System Emulation (SNES): Get the Emulator you want, once again many different choices, I recommend ZSNES, get the game you want, then configure the controls, load the game and play! Hardware Requirements: it's the SNES, if your computer can't handle it, it's time for an upgrade.
Gameboy, Gameboy Color, and Gameboy Advanced Emulation (GB, GBC, and GBA) Get Visual Boy Advanced as it is compatible with all 3 systems, get the game you want ( In other words Pokemon Emerald ) configure the controls, then play! Hardware Requirements: What do you think?
Nintendo 64 Emulation (N64): Get project 64, the official version, not the net-play support version, go through the installation process, then get the games you want, this is where things get different, Project 64, unlike the previous emulators I covered, doesn't have a 100% game compatibility, sorry to those wanting to play FIFA Soccer 64 (Like anyone does) Anyway, don't expect Project 64 to run every game, or certain games perfectly, but it plays almost every game, Also, N64 Games take awhile to download, as they're file sizes are in the 10's of Megabytes, some games like Conkers Bad Fur Day can take hours to download if you have a slow connection, finally, configure the controls and relive your childhood in Hyrule and the Mushroom Kingdom Hardware Requirements: 1 Core running at 500Mghz, 1Gb of RAM, for perfect Emulation you need Daul core, each core running at 2 Ghz, 1.5GB of RAM.
Nintendo Virtual Boy Emulation(VB): Never heard of such a System? Didn't think so. The Virtual boy is Nintendo's Biggest failure, bigger then the GameCube, the Wii U, or SEGA's Dreamcast, It was the first 3D system, so primitive that it gave people headaches and seizures, nonetheless, there is a VB Emulator called VBjn, if you want it, download it at the Emulator Zone because the Emulator Zone is the only Website that has it, get the games and configure your controls, then welcome yourself to Video Game Hell, home of Sonic 06, also, VB ISOs are hard to find Hardware Requirements: Any Computer ever made.
Nintendo GameCube Emulation(GC): There are a few GameCube Emulators, but the best is Dolphin, an Emulator named after project Dolphin, Get Dolphin, then get the games you want, Warning, GameCube are very large files and are always EXACTLY 1 Gigabyte, expect waiting an Hour to get one game, extract the downloaded game to get an ISO file, Configure Dolphins Controls, then run the ISO file, congratulations, your playing a free game that isn't pix-elated with no voice acting, Hardware Requirements, Daul Cores, each running at 2.5 GHz, 1.5 Gigabytes of RAM, to make most games run perfectly I recommend Qaud-Core each running at 4.0 GHz.
Nintendo DS Emulation: I recommend getting DesMume, AND No$hGBA, DesMume is the best DS Emulator, No$hGBA is a GBA and DS emulator, that can play certain games DesMume can't. Get both of them and the games you want, Extract the games to get a nds file, Configure the controls, then play! Hardware Requirements, Daul Core each core running at 1GHz, 1.5 GB of RAM, nothing much.
Nintendo 3DS Emulation: I've seen several different ''3DS Emulators"" online, I think it's fake but can't be sure unless I try it, but I'm not taking the risk, the 3DS isn't a powerful system so Emulation for it doesn't seem to obscure, if you want to try getting a 3DS Emulator, be my guest, if it works, post your results here.
Nintendo Wii U: I've heard false claims of Dolphin running Wii U games, but it's been denied by dolphins official website, so not true, but the Wii U has similar coding to the Wii, so it shouldn't be hard to Emulate, just because Dolphin can't run Wii U games doesn't mean some other Emulator can't!
Well, that's about it, I put a lot of time and effort into this post, I hope it helps, I apologize for any Typing errors.