Idea 1:

Ok here is my idea that could work. You pet battle in your main city (where its posible) against other players.
What you do is that you challange other players via trade and offer them 1000g if they win--- but if they lose a pet battle you gain 1000g from them.
There are a few rules:
*No money overpowered pets (yeah some are).
*You are not allowed too tell other player what setup you will use against them
*If the player logs out and doesnt want too pay out you can make a ticket too game master (for scaming)
*If you draw you lose
*If your pet dies and enemy pet die in same round no1 wins (you have too change pets after this)
*Only lvl 25 pets
*Some ppl can armory your favorite pets soo its a good idea too have at least 10 lvl 25 ready
*You can see pet battle chat so its imposible too cheat your way out of not paying
*As far as i know this is not counted as casino (where casino always wins) because every player has 50% chance too win (and it depends on skill also)
*Advertising in trade shouldnt make any problems because its not a scam
*Due too a rng of the attacks even a good player can lose
*Maximum 1 game against same player (unles a draw) too prevent overlosing money
*You can battle for lower prices-- even 10g, but in this case i would say lvl 10 pet setups/ lvl 15 pet setups and so on (those pets dont lvl if you win)

Idea 2:
Same as above exept in this situation:
*You are giving away some valuable thing or gold if they win against you
*You gain nothing (well maybe some friends)
*Only 1 try
*No lvl cap.... you can battle against lvl 15 25 13 pets against your setup wich can be 25 25 25
*You can have limited rewards and they can be also some transog sets, flasks, food and so on.

But the question is... is that even allowed. Eula says nothing abauth it. Compared too a casino games this 1 is totaly difrent. Its all in skill.