Pokemon Legends: Arceus takes place in the Sinnoh region of Pokemon Diamond and Pearl before it was known as Sinnoh, and includes a number of NPCs that appear to be the ancestors of characters in Diamond and Pearl.
If you're unhappy with the selection of Oshawott, Rowlet, or Cyndaquil in Pokemon Legends: Arceus, it's pretty easy to get one of a few different starter Pokémon relatively early on in the game.
Pokémon Legends: Arceus is an ambitious revamp that successfully revolutionizes the defining Pokemon experiences of catching and battling, but is unfortunately set in a drab, empty, and at times tedious world.