Gray

Because Gray by herself cannot do any campaigns (exceptions: Food and Event) or dungeons, it is often recommended to have her as an Alchemist. She creates at an extremely slow pace, but will still be able to gain XP and create some items if given enough time. Aside from that, she can also fight clones to boost the pet multiplier.

=Graylings/Children= After evolving Gray, Gray creates a child of itself that operates similarly to having another pet. It can be one of three classes: Adventurer, Blacksmith, or Alchemist, all of which have a 0.8% * CL bonus. The Child's growth is always equal to the Mother Gray's growth, and the Child cannot earn growth in Growth campaigns, feeding (the children do not get hungry), or in dungeon events; the growth of the Child will always be equal to that of the Mother. That means the only way to grow Child is by having Gray in Growth camps and by feeding Gray. 60% of XP gained by the Child is "sent" to the Mother Gray, and the two share the same Dungeon Level and Class Level. Since Child 1 can be a blacksmith, you could theoretically put it in dungeons if you want to use it as a dungeon pet instead of a crafting pet.

If you wish to change the class of the Child, use the revert button on its pet page. This will destroy the Child, and you'll have to go back to Gray's pet page and make the Child again. (If you spent a pet token to make the second child, you will not have to spend it again). Equipment will not be lost as long as you recreate the Child, so no need to unequip.

Token Upgrade
You can use a pet token to get a second Child from Gray which can be any dungeon class (Assassin, Supporter, Rogue, Mage, Defender) unlike the first Child. The Class bonus is still 0.8% * CL. The second Child behaves exactly like the first with the Mother Gray, in terms of Growth and XP. The second Child, similar to the first, sends 60% of all XP earned to Gray. This means Gray (and by proxy the Children) will earn 120%: 60% from Child1 and 60% from Child2.