Hi my name is James and I work at Nintendo Treehouse. Questions are okay but I really don't know much, only have info based on what we weren't allowed to ask.

Weren't allowed to ask significance of night and day

Tapus serve as the totem Pokemon for the island champ (most likely, as you must fight it after Hala).

Pikipek likely gains the grass type or just learns many grass moves. (Weren't allowed to ask about the wood pecker aspect)