A poster of what appears to be Gigantamax Toxtricity was in GameFreak's office in Pokémon Sun and Moon (As well as Ultra Soon and Ultra Moon), which came 3 years before Pokémon
GAME FREAK OFFICE IN POKEMON SUN AND MOON - YouTube
Heahea City - Alola - Serebii.net Pokéarth
Pokémon Sun and Moon - Wikipedia
Gallery: Game Freak Has Moved In With Nintendo, And The New Offices Look Sublime | Nintendo Life
Game Freak Offices - More Sidequests etc. - Postgame | Pokémon: Ultra Sun & Moon | Gamer Guides®