Here's the reason I picked each card
-Murcrow:makes your openent not be able to switch.
-slowking:so your openent can't play trainer cards.
-slowpoke:so you can get slowking.
-Brute bonnet:so you can stall with poison on your side.
-arceus:so you can have a offensive option.
-potions:so you can heal
-booster energy:so you can activate brute bonets ability.
-luxprius cape so you can survive.
-energy:so you can have energy.
-Evolution incense:so you can find slowking.
Also I didn't test this deck.