That's actually a common tactic used by Skarmory trainers: Use Spikes, then use Whirlwind to your heart's content, with each Pokémon who comes in taking damage. Don't know how well it works, though.
Got it? Don't ever shift in and out, all right...?See, you're doing it!Well, I am an idiot, actually...SpikesWhirlwindI won't! I'm not an idiot!Aura Sphere!I can't help that!