Rocki, Poofi, Beami, Charmi, and Sparkli all make up the Cosmo Family in Fantage. You must be a premium member to buy the Cosmo eggs (for the traditional 200 stars). But if you are not a premium member, you can still obtain members of the Cosmo family by buying magic codes from Pet Town for a certain number of eCoins. The number of eCoins spent on magic codes depends on the member and the time you want the member to hatch in. (Times come in instantly, 20 minutes, and 1 hour.)
It takes a different amount of settings to hatch these eggs. Here is how to hatch each member:
Beami - medium temp, highest light
Charmi - cool temp, low light
Poofi - warm temp, medium light
Rocki - warm temp, low light
Sparkli - medium temp, medium light