[Azurath TheRider]

I'm thinking something along the lines of a fusion sentai. Three members (red, blue, yellow) have the power to fuse with each other into one warrior. Red+Blue=Violet, Red+Yellow=Orange, and Blue+Yellow=Green. They'll battle some force with the ability to fuse kaijin from previous series. The mecha of the series will be kinda different: each ranger gets two mecha, which can mix and match with each other into 3 Ace-Buster-like mecha, which can furthermore combine into one giant mecha. Throughout the series, they'll unlock the ability to fuse previous Sentai powers and mecha with their own powers.