How do you get diamond cup in rayman legends

You must be in the top 1 percent. Take the number of challengers and multiply it by .01 and that'll be the rank you'll have to get for a diamond cup.

For example, 3020 people have done the challenge, so you have to get rank 30 or higher in that challenge to get a diamond.

Remember that you have to stay in this position untill the end of the day.