Speaking of Espeon & Umbreon being related to the Sun & Moon, this made me wonder if certain Pokemon that have to do with the sun and moon will have any involvement in the game (be it version exclusive, used by an important NPC, and/or their final stages getting a Mega Evolution; I'm just going to list them):
NOTE: Any doubles I list will be striked out. I didn't want to leave them off a list they counted in since who knows what GF would consider a qualifying trait.
Sun:
Day Evolution: Espeon, Roselia family, Chansey family, Tyrunt family, Riolu family
Sun Stone: Bellossom, Sunkern family, Cottonee family, Petilil family, Helioptile family
Shiny Stone: Togepi family, Roselia family, Minccino family, Floette family
Morning Sun: (Naturally: Espeon, Beautifly, Cherubi family)(Breeding: Venonat, Growlithe, Ponyta, Togepi, Sunkern, Pidove, Larvasta)
Sunny Day Naturally: Magmar family, Moltres, Bellossom, Sunkern family, Ho-Oh, Seedot, Castfrom, Cherubi family, Bronzong, Leafeon, Cottonee, Petilil, Maractus, Fennekin family
Drought: Groudon, Vulpix family, Mega Charizard Y
Other: Solrock, Litleo family
Moon:
Night Evolution: Umbreon, Amaura family, Chimecho family, Gligar family, Sneasel family
Moon Stone: Nidoran families, Clefairy family, Jigglypuff family, Skitty family, Munna family
Dusk Stone: Murkrow family, Misdreavus family, Litwik family, Honedge family
Moonlight: (Naturally: Clefairy family, Oddish, Gloom, Umbreon, Dustox, Volbeat, Illumise, Cresselia, Munna, Noivern)(Breeding: Exeggcute, Sableye)
Moonblast: Clafairy, Oddish, Gardevoir, Swablu family, Lunatone, Cresselia, Whimsicott, Flabebe family, Spritzee family, Slyveon, Carbink, Xerneas, Diancie
(Notable) Nocturnal: Zubat family, Hoothoot family, Gastly family, Staryu, Spinarak family, Houndour, Wooper family, Banette, Duskull family, Rotom, Kricketot family
Other: Lugia, Darkrai