I love PokeMMO but I really wish it had more MMO features and more reasons to interact with other players.
I think it would be cool if each player had some stats that they could level up in order to do things that some players might not be able to do with their stats. For example, what if there was a crafting stat that allowed you to make pokeballs with higher catch rates. Of course, the higher a player's crafting stat, the better pokeballs they could make. This would encourage player interaction because if you decided not to spec into this crafting stat and decided to focus on another stat, you would need to seek out a player with a high crafting stat to make you some of those high catch rate pokeballs.
I have a bunch of ideas for stats, such as a fishing stat that, when leveled up, allows you to find rare water pokemon with hidden abilities or special items. A battle stat that increases the critical hit chance in PvE battles, making this stat ideal for the battle frontier. A breeding stat that would drastically reduce the difficulty of breeding once maxed out. Or even a luck stat that increases the amount of an item you can steal from a wild pokemon.
This feature would make everyone's experience unique and would enhance the multiplayer experience. Players with high battle stats would make for desirable battle frontier partners. Players with high breeding stats might get paid for their services. This feature would be really good for player interaction because as it is now, you can play the game without ever having a reason to talk to another player.