The Legends series ISN'T a spin-off game. Its been confirmed as part of the mainline series. There isn't any "pattern" either. You can't establish a pattern with just one game. This is GameFreak's chance to be experimental and try things they wouldn't otherwise do. I think it's very smart of them to not keep all the games stuck in the past—otherwise it would become repetitive. There's only so many "character gets teleported to the past" stories you can do before it loses its charm. Pokémon fans NEED to let go of this idea that the Legends series can ONLY be done while in the past. I think the teaser trailer from last year was a dead giveaway that it'd be modern (set in the future) from the cyber aesthetic.