This page explains how to trade from Pokémon Shining Pearl to Pokémon: Let's Go, Pikachu!.
Trade Not Possible from Pokémon Shining Pearl to Pokémon: Let's Go, Pikachu!
Sorry, but it's not possible to trade from Pokémon Shining Pearl to Pokémon: Let's Go, Pikachu!.
Pokémon can't be traded from newer games to older ones.