Lagrange: The Flower of Rin-ne/WMG

The Big Bad is...
Either Villagillo or Moid

The Power of Friendship will turn out to be a very very bad thing
After all, the Vox units are practically fueled on the stuff, and that certainly amplifies between the three pilots. The whatever the Hell did was certainly within anybody's evil intentions. It's likely Villagilio  with full intent to make the other two Vox units do the same thing.
 * And whatever the Hell will promptly cause Not-Kotetsu Villagilio's defeat the minute he tries to harness it himself.

Muginami is meant not to be an Expy of Mugi, but of Nia.

 * And Not-Kotetsu is Simon.

The Vox were...
Originally made to terraform planets but the pilots lost control and ended up destroying most of civilization on Earth at the time. The true nature of the units were lost to history out of fear towards their power until they are used as they're supposed to at the end of the series.