Ryosayku
What happens after it changes at level 15? o.o Is it all random for what it changes into? you buy a this black egg thing from the cash shop for 5.5k nx and complete this one quest from this dude in NLC(I think thats where he is) and then take the egg and 10k mesos to the dude and it'll randomly evolve into one of the four variants.
It's a repeatable quest too so you can keep doing it until you got the color you want. I think there's a pet evolution guide on the ms website too, I just looked at it on this sleepywood thread ----->
here