Sceptile Leaf Blade
Nighttime Guardian
To what end does he need a complete team? What is wrong with not having six pokémon with you? His current team is fine, it's fun. The ninja bird that can use Razor Leaf to hide and sneak up on foes, Torracat with Flame Charge, power, and determination, Lycanroc with a lot of power and speed through Accelerock, and Pikachu is stronger than ever before with Electroweb and Z-Moves.4 pokemon (5 if he catches Meltan) is not a complete team, and it's not concrete on if Poipole will return (albeit is the best option for Ash to get since he's already bonded with it as apposed to someone random they could've already given him.) and even if the latter came back and evolved, i'm still unsure if that could salvage this team.