You need the emulator app (usually found in the market.) Do a market search for N64 emulator and Playstation emulator and you should get some hits.
You also need the console ROM and the individual game ROMs. These are not found in the market. If you own the consoles and the games, there are ways to copy the ROMs off of them. If you do not own the console or games, it is illegal to "obtain" said ROMs through other channels. As most people usually go with the second option of the two, it is frowned upon to talk about it here.
In any case, look at the emulators in the market and they usually have info on what else is needed.