Guess how many rain teams run perish song politoad? Not many. And perish song is cockblocked by mr. mime. You're also missing the point if you believe taunt shuts down baton pass, espeon is on BP teams precisely for that role. BP is a legitimate strategy that can beat a wide array of teams, particularly bulky offense and stall. Espeon is the face of BP, on top of having great offensive presence, and being a great deoxys-d counter and one of the best DS users, that's why it deserves B rank.