With the vs seeker coming soon™ players might have more money then they can handle! Which is why i suggest some PVP staking!
It could work in a number of ways, with optional rules to change how the battle flows, rules like:
1. No status moves
2. No switching pokemon
3. No items
4. Moves do double damage
5. No stage modifiers (hail, rain dance, sunny day, sandstorm)
6. Level limitations
use your imagination
Stakes could also include other things besides money, things like items, and pokemon.
But with high stakes gambling there should be some rules and requirements to keep balance so new players don't lose everything.
1. Players with less than 2 badges should not be able to stake.
2. Players should be warned to the opponents high level pokemon (this already exists in regular battles).
3. Players should only be able to stake with a player that has an equivalent number of badges, this should also keep balance between players with 2 badges fighting a player with 8.
4. Players should not be able to stake all of their money and pokemon, it should stop at a reasonable number (for example you cannot stake money if you have less than 5k, and if you have 20k, you can only stake 15 of it)