Mew is a coveted Legendary Pokemon in "Pokemon SoulSilver" that is known for its ability to learn any special move in the game (HM and TM moves). The Pokemon is absent from the game's normal gameplay, so you will need an Action Replay device to get the Pokemon. The Action Replay device is a third-party peripheral that allows players to use cheat codes on some of the Nintendo DS's most popular games, such as "Pokemon SoulSilver." The device should come packaged with a USB cord and the device's Action Replay Code Manager software.
Connect your Action Replay device to your computer via the USB cord that came with the peripheral.
Open the "Action Replay Code Manager" software on your computer. The program will automatically detect the connected Action Replay device.
Right-click on the "My Codelists" panel at the bottom-right of the screen.
Click "Add new cheat." A new, small window will appear.
Enter the Mew's Action Replay code into the window:
Give the cheat a name and click "OK" to save the cheat. The code will automatically be uploaded to your Action Replay device.
Attach the Action Replay device to your handheld console.
Load your saved game of "Pokemon SoulSilver."
Go to any PC in the game. PCs can be located in any "PokeCenter" in the game, typically at the top-right corner of each of the buildings. The Pokemon will be contained in the first slot of the first storage box.