Right know there is some confusion going on, what Pokemon Let's Go actually is. Let me tell you it's not a Pokemon Yellow Remake and it's not a Gen. 7 Game.
-The Game takes place in a complety new Kanto. It is a full 3D Third Person JRPG and not a 3DS Game in HD based on a Layout of 1996 Gameboy JRPG.
-There are new Pokemon, most of them are Evolutions of already known Pokemon (mainly from Kanto), and there are also knew Regional Forms for some Non-Kanto Pokemon.
-Instead of having new Starters GF had the idea to use Pikachu an Eevee. Both get new Evolutions. Gorochu is back. Eevee is finally getting a Normal Evolution Line.
-Your Pokemon can follow you (not only Pikachu an Eevee), Wild Pokemon are also shown in the Overworld, No Random Encounters
-Catching Pokemon is still like in the older Pokemon Games, a new Element inspired by Pokemon Go is that you can throw a Ball via the Touchscreen (in Handheld Mode) or with Motion (Docked Mode).
-Pokemon from Pokemon Go can finally be brought into the Real Games via the Pokemon Bank.
The Game will be revealed soon.