It is random but in some point, you may see some pattern .. For example, me, the most chakra i have is the Lightning Chakra, like i have 200 of those and the other element, i only have 50 .. Then one of my groupmates have this Fire Chakra stacking up high and his other chakras was so low or even none .. Then the other one has a lot of Water Chakra .. So .. whatever, Trading is what you need .. They put that feature for this very thing ..