To open the Rescue Center, you just need to tap on it. Once you have done so, you will open a screen where you can trade your pets. You can choose to either sell your pet for coins, or trade two pets to get another pet of a higher star value. For pets with the level 1-3, you will be charged some coins to trade the pets or be able to sell for coins. If you choose to sell level 4 or 5 pets, you will gain some diamonds, and if you wish to trade level 4 pets, you will be charged diamonds.

The Rescue Center will only show non-active pets, so if you are using a pet, you will not be able to trade it. You are also only able to trade pets from the same rarity level. You are not able to trade 5 star pets, but you will be able to sell them for diamonds.

In order to trade a pet, simply tap on the pet you would like to swap. You are able to add two pets at a time. You will be asked to confirm that you would like to trade the pets. Once you confirm, you will be given a new pet.