This can be achieved after earning the power-up Xochitl's Blessing which forms a match with any colour surrounding it. Once you collect it you must drop it in an area where it creates a match with at least three colours. It's quite a tricky one to get as you can't afford spend too much time thinking about it as the blocks rise throughout the game. You will get two colours quite easily but three is going to take some time, I got mine in level 3-1 for instance.
Just try to look out for a good spot for two colours and try to quickly add a third on top of it. You may even get lucky and get it when you least expected. One other note, if you have your mind set on going for this avoid collecting the Jaguar's Strike power-up as that takes out all the blocks of one colour and just about kills your chances of getting it.