I don't have all information but I can say some issues:

Pancham would evolve with trade.
The conetion Ash/Greninja is a clue for this generation.
Eevee evolutions will be important.
Sylveon new counter (Eevee new evolve-Steeleon?)
Kalos history is conected with Alola (Travel to Kalos?)
Pokemon Z? We'll see Zygarde end history.
Ash/Pikachu?
Serena and Ash would travel to Alola.
Marshadow types steel/dark (advantage over Lunala and Solgaleo) a little copy for Black&White.
4 fairy guardians with startes types: grass/water/fire and electric who was reveal and Magearna history.
The anime Pokemon XY & Z would spoiled about The future of The franchise.

That's all I can remember now.