Instructions
Start "Super Smash Bros Brawl" and select "Options" from the main-menu. You will see a list of items that you can set to "On" or "Off," and a selection for item frequency. Set the frequency to high, which will make items appear more often in game, and set every item to "Off" except for the "Pokeball."
Start a regular match with as many players as you like. Wait for the "Pokeball" to appear in the game, then grab it with "A" and throw it by pressing "A" again. A random Pokemon will be released into the playing field.
Keep throwing "Pokeballs" until a flying blue Pokemon appears. This is "Manaphy," and if you're standing close enough to it with another player, your characters will switch, giving you access to its move set.