Okay, so, I haven't played any mainstream Pokémon games aside from Moon, Ultra Moon, and Sword, but here are my starter choices for each generation:

Generation One: Charmander

Generation Two: Cyndaquil

Generation Three: Mudkip

Generation Four: Chimchar

Generation Five: Tepig

Generation Six: Fennekin

Generation Seven: Popplio

Generation Eight: Scorbunny

(I chose them all based on stats and other factors, and that system just so happened to favor mostly fire types)

Also, here are the game choices:

Red or Blue: Red

Gold or Silver: Gold

Ruby or Sapphire: Sapphire

Diamond or Pearl: Diamond

Black or White: White

X or Y: Y

Sun or Moon: Sun (I bought Moon, but if I had the choice today I would pick Sun)

Sword or Shield: Sword