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