- Something cool would be to make half of the mata one character and the other half another (Think Pokemon Trainer) It may seem stupid, but it will make more sense later
- Make Takua/takanuva like Samus/Zero suit
- Remove Takutanuva
- Replace Hahli with Matoro
- Remove Vahki
- The Shadowed One is a must
- Takua/Takanuva's could be something "don the Avohkii" and then "revert to takua" when he is Takanuva
- For Takanuva as a seperate character, it could be "Takutanuva"
- Teridax (maybe other G1 Makuta) could have "Shadow Hand"
- Teridax might also have "Reign of Shadows" where he controls the universe (stage) for a short time creating chaos for all on the stage
- Tahu or Vakama could have "Vahi" where everyone slows down except for him
- If you do the 3 mata for 1 fighter thing mentioned above, the Final Smash could be to for the Kaita
- Brutaka could have his final smash be his Antidermis form (think Super Sonic)
- Vezon/Fenrak could have "Kardas Dragon"
- Any Barraki character could sommon his army for the final smash sort of like Pit's (pun sort of intended)
- Ignika could have "life drain" (maybe similar to Kirby's? I don't know)
- Nuva forms for the Mata
- Twilight Takanuva
- Maxilos could be an alt of Teridax
- Omega Tahu as an alt of Lhikan
- If you insist on the vahki, maybe as an alt for Matau Hordika
- Botar could be an alt for Brutaka. Maybe
- I feel like Ignika and Mata Nui should be alts of each other. Maybe have Ignika without his board?
- Lastly, Makuta (G2) and Ekimu should be alts for each other
- Master Hand could be Tren Krom
Edit after reading the rest of this topic, I have a few comments:
I like the idea, but I think takua and takanuva would not be able to keep a similar enough move set. Maybe Tanma/Takanuva would be better for that purpose.
I do like Antroz more than Chirox, but I feel that Chirox would have a more unique fighting style, so My vote is Chirox (I know that there isn't an actual vote)
Maybe, it depends on if you want the final boss to be an in-joke or have story significance.