Jirachi, Vaporeon and Togekiss are all good candidates. Vaporeon and Togekiss can both Baton Pass (and hopefully be slower than their opponents) and Jirachi can U-Turn.
According to Dragontamers defense tiers, Jirachi is the best overall at taking hits, with it's 100/100/100 defenses. You also have to look at weakness's though. Vaporeon is only weak to Electric and Grass, while Jirachi is weak to Ground and Fire, two very common attacking types. Togekiss is weak to Stealth Rock (25% just for switching in, eww) and is weak to electric, ice and rock, 3 very common attacking types.