I get the frustration of some of the other comment writers on here. personally my favorite is the (n64 emu) not mupen64 plus, a lot of great emulators were left out. PPSSPP for example, it takes a lot of data space to hold your games, and yeah your going to need something like Zarchiver to unzip your files, but right there in the palm of your hand you've got a make-shift psp. Not to mention the Nintendo DS. How can you leave that out. DraStic nds emulator is an emulator specified for Android smart phones and i can almost guarantee that it'll run any games you have at full speed. yes it cost $7.99 unless you obtain it illegally somewhere else, and it won't work on a tablet. But the information should still be there. Other great emulators like. Fpse the playstation 1 emulator is great and all but you can get nearly the same results by downloading ePSXe or psx4droid. Gameboid is a nice option, but even the demo version MYBOY (gameboy advance emulator) is better. The paid version will never let you down even if you told it to.
With the variety of emulators out there any smartphone owner has the potential to turn there device into a 20 in 1 game station.