These cards increase the amount of damage that you do, or damage your opponent's Pokémon without attacking so that it will be in range for a KO when you attack.
Note that you can combine multiple buffs for more damage, but only one Tool, one Stadium, and one Supporter at a time. Some Abilities don't stack, and neither does Poison/Burn. Also, using a damage-boosting Supporter will cut you off using Boss's Orders to drag in a different target.
Bench Attackers has some Pokémon with Abilities that can set up KOs by damaging the opponent's Pokémon before attacking.
Combos with Munkidori to guarantee that your opponent will receive the damage, regardless of the flip.