[Tokumonkey]

Well, that... is definitely a lot of pieces tacked onto the main mecha.

It's weird that the three pieces are visually cohesive (and probably a strong hint as to the sixth hero's color scheme), but even when all combined, they don't lend that cohensiveness to the full combination. A multiple-mecha sixth hero is hardly unprecedented (off the top of my head, Zyuohger and DonBrothers). No indication that the three can directly combine in these images., so maybe there's another black-and-gold mecha that ties these together?