In a game featuring four New Zealand internationals, the Vipers beat the Western Storm by seven wickets with seven balls to spare.
Rachel Priest scored 57 off 55 balls as the Storm made 140 for five, Bates taking two for 37.
Bates then struck 52 off 46 balls, and fellow international Sarah McGlashan an unbeaten 21 as the Vipers reached 143 for three.