For this I think we should look at habit:
Book 1: Stone, Jungle, Ice, Water, Earth, Fire
Book 2: Jungle, Earth, Fire, Ice, Water, Stone
So Windham has, both times, listed Fire and Earth together, Ice and water together. So that leaves Jungle and stone together. In this case fire went after Earth and water after ice, but we can swap them around. In an ideal world the names are ordered by highest price point elements.
So Fire, Earth, Ice, Water, stone, Jungle. But let’s stick to habit. Windham lists the 6 fallen Toa in this elemental order.
Stone,Earth, Fire, Ice, Water, Jungle
Now let’s look at how the 6 Toa are introduced at the bridge in book 1:
“Onua, Gali, Kopaka, Lewa and Pohatu”
So that’s Earth, Water, Ice, Jungle, Stone and Fire
So let’s look how they’re introduced segment by segment in book 1:
Stone, Ice, Water, Fire, Earth, Jungle.
Protectors:
Book 1: Stone, Jungle, Ice, Water, Earth, Fire
Book 2: Jungle, Earth, Fire, Ice, Water, Stone
Toa:
Book 1: Earth, Water, Ice, Jungle, Stone and Fire
Book 1: Stone, Ice, Water, Fire, Earth, Jungle
Book 2: Stone,Earth, Fire, Ice, Water, Jungle
If we were to put these into circular diagrams (with last being paired with first), they are always paired with the same element with the exception being book 1 protectors which would be a simple straight line pairing.
Earth+Fire
Stone+Jungle
Ice+Water
Ice is, for the most part, before Water, with one exception. The other two pairings are equally swapped.
Ice+Water are always in the middle so we can assume they wont be first and last.
However, in book 2 the mid section introduces Earth, Fire, Ice, Water for both Toa and Protector. Following that trend:
Udapo is Earth,
Owa is Fire,
Epolim is Ice
and Kerato is water
Which leaves either Agarak and Mamuk as either Jungle or Stone. If we follow habit:
Agarak is stone and Mamuk is Jungle.
My conclusion, I think:
Agarak is stone
Udapo is Earth
Owa is Fire
Epolim is Ice
Kerato is water
Mamuk is Jungle
Side notes:
Agarak-(When I looked up Agarak it came up with various stone formations and even snakes, along with some sand and a minority being dogs and grasslands. Coincidence, probably)
Udapo- Nothing
Owa- Nothing
Epolim- (Polim, kinda like Polar)
Kerato- (Similiar to Kivodo)
Mamuk- nothing. Guess it sound jungly.