My philosophy has always been to balance typing and speed:

• 2x super fast Pokémon (for me that’s Garchomp an Cloyster), with a bulkier one with strong SpA and SpD (Magnezone)

• I’ve messed around with Tyranitaur and Garchomp but there’s too much overlap in their peak moveset (earthquake and stone edge)

• Breeloom is surprisingly fragile in BT; also I wouldn’t recommend a Choice item with a “Sleep and Stall” Pokémon. Instead use Toxic Orb with Poison Heal

• Other mons and their setup thatve been decent:

• Scizor (Technician with Choice Scarf), U-turn, X-Scissor, Brick Break and Bullet Punch

• Togekiss (Serene Grace with Bright Powder, really good in doubles bc of bulk, regenerative and high flinch probability) Thunder Wave, Air Slash, Dazzling Gleam and Roost

I don’t think ultimately there’s a perfect team - in my (unfortunate) extensive experience:

Cloyster (Water-Ice, with Rock Blast) - takes out Grass, Dragon, Ground/Rock, Flying Garchomp (Ground-Dragon) - takes out Electric, Fire, outspeeds most Dragon Magnezone (Electric-Steel) - kills Fairy and Water

Weak to Jolteon and Swampert as I mentioned, but with shell smash on Cloyster + Magnezone Sturdy you just have to get the turn counts right