The surprising list of consoles (including the emulator used, in parentheses,) that RetroArch can emulate includes: PlayStation 1 (PCSX ReARMed), Super Nintendo (SNES9x Next), Nintendo Entertainment System (FCEUmm / NEStopia), GameBoy / GameBoy Color (Gambatte), GameBoy Advance (VBA Next), Arcade (Final Burn Alpha), Neo Geo Pocket Color (Mednafen NGP), Virtual Boy (Mednafen VB), Sega Genesis/Mega Drive (Genesis Plus GX), Sega Master System/Sega Game Gear (Genesis Plus GX), Sega CD / Mega CD (Genesis Plus GX), PC Engine / PC Engine CD (Mednafen PCE Fast), WonderSwan Color / Crystal (Mednafen Wonderswan).
As if the complete catalogs of all of these video game consoles weren't enough, RetroArch Android also allows you to perfectly emulate Doom 1, Doom 2, Ultimate Doom and Final Doom. The reason is that you can't be king of the emulators without emulating Doom.
However, RetroArch doesn't come with the ROM of any video game. The emulators do come in a series of Libretto folders, but you will have to download the ROMs separately from any other webpage.
RetroArch is by far the most full-featured emulator out there. Other emulators can offer you access to the catalogs of one or two different consoles, but RetroArch can potentially emulate thousands and thousands of games.