Now, there is a bit of conflicting information between OJ and Guzma. Guzma, for example, stated that the fossil Pokémon are a sabretooth tiger and Wooly mammoth, while the OJ leak believes it to be a velociraptor and stegosaurus. Though both stated that you got one or the other during the rock trial on Ula'Ula island, which they both claim to be the third island.
Another difference is that Guzma claimed there are four trial captains on each island. However, OJ claims there to be 2 on Melemele, 4 on Akala, and 2+ in Ula'Ula (as it's currently a work-in-progress.
According to OJ, Melemele's trial captains are Normal and Bug-type, which feature the Totem Pokémon Gumshoos and Cutiefly's evolved form.
In Akala island, the Grass, Water, Electric, and Fire totems are apparently going to be Lurantis, Bruxish, Vikavolt (which he claimed was arguably the toughest fight in the game), and Salandit's evolved form (presumably based on a komodo dragon).
And finally, of the Totem Pokémon encountered so far on Ula'Ula, the ones revealed so far are the final evolution for Pikipek, and the evolved form of Minior.
Ironically enough, the only predictions so far concerning the Totem Pokémon that I was way off was the Flying-type Totem. Apparently, they are not on Melemele as I thought it'd be, but rather on Ula'Ula.
I am, however, fond of the idea that the evil team leader is going to steal the third Starter after some time on the island, though I'm convinced that you will end up seeing all three starters recorded on your Pokedex all at once no matter what when you first select your Starter. Why? Because unlike in past games, all three Starter Pokémon are out in the open for you to select at your leisure (rather than inside a Pokeball).
I have predicted, however, that the remaining trials on Ula'Ula are going to include Ghost, Ice, and Fighting as well as Rock.