Read the Boo deke. Chances are they charge-deke-charge. If they're like the mediocre players I keep seeing in single player, they deke in one direction, usually down or back. Run up to them, but don't tackle them until they use the deke.
Know where their shooters are at all times. If you're just aware of where they are, then you can most of the time beat them to the ball.
Learn to pass-intercept. Instead of clearing the ball with kick, if you can get the hang of hitting A right before they're about to shoot, it really throws off their team.
Keep the ball. Get up by 1 or 2 and try to keep it away from them. Keep passes low or on the ground.
Hit them. A lobbing team can't use their items 100% effectively (read: they don't have many interior sure-goals. Diddy's flip, Boo deke are a few of them.) When you knock their game out of rhythm, that's when they're the most vulnerable.
Switch either your captain or your Koopa. Straight up, it's a waste to have 2 balance characters imo. You should add a power shooter or a Hammer Bros. but that's just my opinion.