Head over and talk to Koopa the Quick, he’s right near the start so you can’t miss him.
Bob-omb Battlefield Star 2: Footrace with Koopa the Quick Make sure to not throw him off the mountain at any point or else you’ll need to restart the fight. Once you reach Big Bob-omb you’ll then need to grab him from behind and throw him three times. Make your way to the top of the mountain avoiding the likes of the giant chain chomp, falling water bombs and rolling balls along the way.