In order to unlock the locked Battle Games, you must complete the game at the highest available difficulty. In order to unlock a new Battle Game, such as Flag Competition, you have to complete the hardest level of the game before it (in this case, complete Battle Competition at hard to open Flag Competiton). To unlock Donkey Kong as a driver, beat him in any Super Duel competition on hard difficulty. There are also some locked machine parts. If you beat DK in any hard Super Duel competition, you unlock the DK Body, DK Engine, DK Tires, and DK Weapon. If you beat all three games in all three difficulties, you unlock the Skolar Body, Skolar Engine, Skolar Tires, and Skolar Weapon. After you purchase all 44 machine parts, Bob-omb Wall and Bowser Punch become unlocked.