[Matrixbeast]

This is a neat idea, but popular vote does lead to some issues, primarily in that the more popular characters would advance much easier, despite their apparent weaknesses (I'm particularly afraid of Double's Dopants getting ahead in an unfair manner).

Anyway, I'm gonna vote Makamou simply to the form of hierarchy
While I have yet to see Kuuga or Hibiki, your description of the Grongi does make them sound strong, but if they're willingness to grow is so great that they care nothing for fellow Grongi, then I think the Makamou would have them beat.