If you want to level pets while win trading there are a couple problems.
i) If one player is set to win all the matches, then that player will eventually run out of pets that match the level selected in the UI.
ii) The players may have different levels of pets, different numbers of pets, different quality of pets.
Here are some features that might help with the above:
1) Have an option to allow teams with non-rare pets. This will increase the selection of pets. Also, those non-rare pets will be upgradeable eventually by all the stones that will be won. The pet choices should prioritize rare pets over non-rare pets since a pet will loose a level when upgraded if it is higher than level 15. This option should probably only apply to win trading.
2) Add an option to create matching teams between win trading players based on matching levels. The addon of each player communicates to the other player the quantity of each pet level. If the player is set to use non-rare pets then it should also communicate the same for each quality so that pet selection can be prioritized by quality. Quantity only needs to be a number between 0 and 4 - where 4 means they have more than 3 pets of that level). The addon for each player then takes that list, and selects the 3 lowest level pets that will match the list. Then the addon joins the queue. This option overrides the team level option or else the team level option can be used as a minimum level. The addon should also communicate if the player is set to forfeit. The forfeiting player can select non-rares since they will loose and not gain a level. The forfeiting player will select the lowest level team of any quality that matches the winning player's list of lowest level rare quality pets.
2b) Add an option that prioritizes creating matching teams starting from the highest level instead of the lowest level. Do higher level teams give more player XP?
2c) If you add 2b, then you need an option to start at level 24 if you're purpose is to level pets.
3) Add an option to preserve a quantity (a number between 0 and 3 or maybe even higher) of pets for each level. This means the team level matching will not choose a pet of a level if the player does not have that number of pets at that level. This way, the player will retain a set of different level pets that can be used to level the pets of another player.
If you want to level pets while win trading there are a couple problems.
i) If one player is set to win all the matches, then that player will eventually run out of pets that match the level selected in the UI.
ii) The players may have different levels of pets, different numbers of pets, different quality of pets.
Here are some features that might help with the above:
1) Have an option to allow teams with non-rare pets. This will increase the selection of pets. Also, those non-rare pets will be upgradeable eventually by all the stones that will be won. The pet choices should prioritize rare pets over non-rare pets since a pet will loose a level when upgraded if it is higher than level 15. This option should probably only apply to win trading.
2) Add an option to create matching teams between win trading players based on matching levels. The addon of each player communicates to the other player the quantity of each pet level. If the player is set to use non-rare pets then it should also communicate the same for each quality so that pet selection can be prioritized by quality. Quantity only needs to be a number between 0 and 4 - where 4 means they have more than 3 pets of that level). The addon for each player then takes that list, and selects the 3 lowest level pets that will match the list. Then the addon joins the queue. This option overrides the team level option or else the team level option can be used as a minimum level. The addon should also communicate if the player is set to forfeit. The forfeiting player can select non-rares since they will loose and not gain a level. The forfeiting player will select the lowest level team of any quality that matches the winning player's list of lowest level rare quality pets.
2b) Add an option that prioritizes creating matching teams starting from the highest level instead of the lowest level. Do higher level teams give more player XP?
2c) If you add 2b, then you need an option to start at level 24 if you're purpose is to level pets.
3) Add an option to preserve a quantity (a number between 0 and 3 or maybe even higher) of pets for each level. This means the team level matching will not choose a pet of a level if the player does not have that number of pets at that level. This way, the player will retain a set of different level pets that can be used to level the pets of another player.