I think my best Pokemon team in the game without legendaries is:
Beedrill: Level 78 (Olol Day-Care forgetfulness)
Ditto: Level 80 (holding a Sitrus Berry IDK why...)
Typhlosion: Level 79 (holding a Zoom Lens for its moves)
Kingdra: Level 83
Poliwrath: Level 79 (holding a smuggled Jaboca Berry)
Tyranitar: Level 73 (holding a Zoom Lens as well for Stone Edge)
You wouldn't imagine all the Legendaries I imported. But the problem was I didn't want to import strong Legendaries and sort of have a challenge, which was the hardest part until the battle against Red came along...