Crackpot theory time: in the key art for the Teal Mask there are a bunch of lanterns with type symbols on them, which have been speculated to be hints at the types of the loyal three and Ogrepon:
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Khu highlighted the lanterns recently, too. Given that the loyal three have Toxic chain as an ability, they likely share Poison. The most recents presents had a scene in which Munkidori used a psychic move, Fezandipiti used Moonblast, and Okidogi used something like Giga Impact but could possibly be an updated Meteor Assault, which could hint at Psychic, Fairy, and Fighting types for those three. Then, we've also seen that the balloons in the ogre busting minigame have grass, fire, water, and rock symbols on them.
This accounts for all of the symbols except ghost and the ogre symbol. Possibly then Ogrepon could be part ghost, which if it were dual-type in all its forms would make it the first rock/ghost, third water/ghost, and seventh grass/ghost and fire/ghost lines. :P (But, if its mask changes its type, then possibly it acts more like terastallization and becomes mono-type depending on which mask it wears).
Presumably the ogre symbol is just representative of the ogre story, but I guess there's an outside chance it's the 20th tera type. (Though it'd be weird if part 1's special tera type were revealed before part 2's, so I wouldn't bet on this).
