With some adjustments, I believe it has potential to be brought back from the dead somewhat. I'll propose a few ideas.

First, is to allow players to fight each other in battlecages. Here's the catch: You are required to team with your monster. So how do we command our monster if we aren't on the commanding platform? We can either have a friend on it to command it for you, or a NPC will be stationed to issue random commands in the event your friend doesn't show up and/or if you don't have anyone to.

There are four battlecages. Have two of them to be monster-only fights like they are right now (primary use is to level our monster), and the other two to be player+monster team fights.

As for the rewards, well. To watch players fight in battlecages can be exciting. Winning player+monster team fights would yield more Jettons than winning monster-only fights (player+monster more for Jettons, monster-only more for monster exp). Maybe throw in trophy furnishings with decent storage to buy Jettons with, and have them to cost high enough to encourage doing player+monster team fights where more Jettons are yielded.