Here is where we can think of plot twists that would kinda make sense (or just be completely absurd).
For example: Tuma died. Makuta transferred his consciousness into Tuma’s body half a second before the moon collided into the giant robot’s head. Tuma is dead. Makuta lives. dramatic music plays
Plot Twist: Makuta does not actually exist. He said he was nothing, and it’s true. The Toa, Matoran, other Makuta, Turaga, Roodaka, and all the other BIONICLE characters that interacted with him where hallucinating.
Plot twist: When Vakama turned evil he stayed evil, but decided his rule was better served along side Matau.
So, Matau and Vakama hatched a plan to overthrow Roodaka and gain control of the rest of the Toa Hordika.
When they left for Metru Nui (after they reverted to Toa Metru) Vakama said he would return because he needed to find the Mask of Time.
He made a plan with Makuta to give Mata Nui enough time to almost die by holding the Toa Mata summoning stones hidden.
But, Takua found the stones and summoned them.
When the Toa where fighting Makuta, Matau was sent to activate the Bohrok.
Although once he did they captured him and the rest of Le-Koro was captured because of this.
That’s why the Bohrok already did so much damage when the Toa came out of the Kini Nui.
Vakama also knew way too much about the Bohrok, Kranna and powers.
Vakama always used “visions” as a way to explain away why knew so much, but it was really because of his connections with Makuta.
Lhikan is the true villain, and a Great Being, though he is still against Teridax. He conspired with Nidhiki to kill the other Mangai, though he betrayed Nidhiki at the last minute. He created the Toa Metru to get Teridax out of his plans. Then he conspired with Roodaka to take over the city once he died. He died, but instead of heading to the Red Star, became a ghost and possessed Kapura, who went insane. Kapura took drugs to lessen Lhikan’s effects.
PLOT TWIST: Tahu was supposed to use the Vahi in the battle against the Bahrag, and it was supposed to transform into the Vahi Nuva, which would be given to Pohatu later. However, this did not come to pass, Instead, Artahka stole the legendary Kanohi and transformed it himself, then, gave it to Pohatu with his Adaptive Armor.