So I need to get myself an Assault Vest and I have no BP. What Pokemon should I use?

Here's what I have

Jolly Garchomp
Natural Gift Talonflame
Two Gastrodon, one specially defensive one physically
Specially Defensive Venusaur
Manectric with HP Ice
Specially Defensive Sylveon with the usual egg moves
Dread Plate Bisharp
Excadrill without Iron Head
Both Calm and Timid Heatran

I think Garchomp is a must. I'm thinking Focus Sash Garchomp, Air Balloon Magnezone, and Mega Venusaur?