How do you defeat elite four flint?

Elite Four Flint Squad Rapidash male Lv.58 Fire weak against WATER Infernape male Lv.61 Fire/Fighting weak against WATER, Ground, Flying, Psychic Steelix male Lv.57 Steel/Ground weak against FIRE, WATER, Fighting, Ground Lopunny male Lv.57 Normal weak against FIGHTING Drifblim male Lv.58 Ghost/Flying weak against Electric, Ice, Rock, Dark