Pets

Many people have asked me about pets in this game so I'm going to try and answer everyone all at once here. The best pet in the game is the air spirit. He is only attained through diamond summoning which costs real money. Agamemnon is just as good as him and is found the same way. Outside of those two there are no other comparable pets to them. That being said if you are looking for a good pet here are some thing to consider. Are you building offensive or defensive? Are you ever planning on spending money on diamond summon? Are you willing to wait and save wishing crystals to have an epic pet?
    Once you have determined the answer to those questions here some info that should help.
The earth spirit has one different ability from the air spirit. Granted it's the one that makes him so powerful, but the earth spirit is free to summon and you should get it within your first few days. In my opinion the earth spirit is the best free pet. However, it's not noticeable better than the fury goblin,dark spirit,guardian or watchmen.
The dark spirit and goblin are both good offensive pets, giving you a lot to your base attack and some other cool abilities to boot.
The guardian and watchmen are the best two defensive pets, giving you huge defensive bonuses and shield triggers and such. The most important thing to remember though is that power wise, the earth spirits 1 second cool down reduction is more powerful in the late game than any other ability you can get from a pet aside from the air spirits crit damage increase.
Hope that helps you decide which pet to use.

Now for evolving a pet. I have only made it to +3 thus far so I'm not sure what exactly it takes to make a pink. In order to turn a blue pet purple you need a lvl 30 purple pet to evolve it. Purple pets are gained through the diamond summon or by opening the daily summon box and collecting fragments. Once your pet is purple you will need to level it up a bit and then you will need 2 level 40 purple pets to evolve your pet to a purple +1. 3 level 50s are needed for +2 and 4 level 60s for +3.
A tip with evolving, if you have the pet required and it's still saying you don't have enough, make sure the pets aren't in your magical formation or locked.