Instructions
Pick a character that you enjoy using. Each character has advantages and disadvantages. For example, Kirby has fairly weak attacks but can float nearly indefinitely, avoiding getting knocked off the screen.
Open the "Moveset Creation" menu from the opening screen. Select your character and open up his move list. The moves correspond to certain button presses, which you will see displayed on the screen. For example, pressing "A" may trigger a simple punch in Snake while causing Mr. Game and Watch to throw bacon.
Click on one of the button-press options to open a list of possible moves. These moves come from the game characters. There are three move subset options available in your moveset: normal, special and smash. Each button press and subset has specific moves you can use. Use the gamepad to scroll through the possible moves and click "Test" to watch the move. Select one for the button combination. Repeat this process for each possible button combination in all three move subsets.
Try out your moveset in all gaming modes. Each game mode focuses on slightly different action. The battle mode features straight up battling in stages that change rapidly, including an F-Zero race track where you must avoid cars. The story mode features running through stages, avoiding falling through platforms and solving puzzles.
Repeat Steps 3 and 4 if you find your moveset is unusable in any of the game modes. Keep in mind that not all characters are created equal, so your moveset may be weaker in some areas. However, all characters are usable in all game modes, so your character must be as well.