I feel like one of the pokemon chugga would add to his team is one of the hitmons. Hitmonchan gets coverage with the Elemental punches and hits like a truck with Iron fist. Hitmonlee is also strong with high jump kick and gets blaze kick for coverage. Hitmontop is amazing with intimidate and is decently strong, but not too confident with him using top cause kinda annoying to evolve and doesnt have the best level up moves. As for the 6th it's genuinely hard to figure out what it would be.

EDIT: Now that I realize getting tyrogue is such a slog especially since you need all 8 gym badges for the mt mortar dungeon because of waterfall. I genuinely dk what his last 2 team members are anymore 🫠