The Mabu Defense Force is a paramilitary group formed by Mabu, introduced in Skylanders: Spyro's Adventure who are forced to take action when evil threatens their way of life. The army is dedicated to defending other Mabu and the peace. General Robot is the commander of the Mabu Defense Force.
Interestingly, for a paramilitary group, the Mabu Defense Force is primarily focused on aiding Skylanders, simply through non-combatant roles, such as being a medic or engineer. This is further emphasized by their practical uselessness during the first game, when the Mabu Defense Force attempts to hold off Trolls, but as they have no weapons, they are easily overrun, forcing for them to call for backup from the Skylanders.
In Skylanders: Trap Team, the Mabu Defense Force is now shown to be capable of holding their own against enemies for a short while, taking down obstacles and building platforms for the Skylanders to reach certain areas. Buzz is the commanding leader of the group in this game, and the general appears to have been replaced by Rizzo.
In The Future of Skylands, the Mabu Defense Force appears to have replaced the Skylanders entirely as a primary defence force as mentioned by NPCs in the level at random points, but in their struggle against Wolfgang, they had to resort to acting undercover as the resistance.