Is it possible to add a 4th Team?

I have this Romhack in the concept phase where the plot revolves around mediating a war between two nations and such I wanted to add at a 4th Team that is aggressive to Player, Enemy and Ally Teams so I could create chapters that revolve around using the chaos of the battlefield to take key areas with relative ease or to have bandits fight the enemy army in certain chapters.

Is it possible to create a 4th team? If so, what is a good Color for this 4th team to be distinguishable?

I haven’t tried myself but I think this might be what you’re looking for?