Pets are divided into three different rarities: R, SR, and SSR. Each rarity has a certain percentage and they add on an extra win rate to your PvE combat lineup. The higher level Pets will bring a higher PvE win rate add-on. You don’t need to match the level of your pet with the PvE combat level. The level of a Pet will only affect whether it can participate in PvE and the Win Rate Add-on it brings.