Hey here are some hints you might find helpful.
1.Beat star battle and you get 200 carnival tickets and a speciel character
Beat it again with the character you just unlocked and get the 2nd character
You can unlock.(this is a good way to get tickets because you get 200 each
2. You can't buy all you minigames....Some minigames are like battle or duel minigames, you can't buy them you gotta unlock then my yourself.