Is this for stocking a 5 gallon tank or is there another tank you have on hand?
If it's for the five gallon tank, goldfish as already mentioned, are an incredibly poor stocking choice for a tank of this size. When not stunted by small tanks and poor water quality, goldfish grow very quickly, and even the fancy goldfish grow to quite a substantial size.
White cloud mountain minnows are very active schooling fish. They need to be kept in a group with a minimum of six individuals, and a five gallon tank does not offer them adequate space to move around in. I personally think a 15-20 gallon tank is the minimum for a group of these fish.
This is a link from a very reputable site outlining the requirements for keeping WCMM.
Guppies are probably the best choice out of the three fish species you have listed, to go into a 5 gallon tank. I would think a small group of males should be okay, but I have only had limited experience with these fish.