Instructions
Select Diddy Kong as your character at the character select screen.
Select the options menu from the top of the battle screen and go to the "Items" option. Change the item frequency to "Very High." If you wish for only Pokeballs to show up, turn off all other items. Make sure Pokeballs are turned on.
Select your battle stage and press "Start" to begin the battle.
Press the "A" button when you are next to a Pokeball to pick it up. To shoot it out, press either forward and the "A" button" or any of the four directional "C" buttons.