Gyarados vs Milotic | Bulbagarden

Dragon dance thunder milotic dies.

This is a terrible idea. Expanding on what Jesus said (lol, I can't believe I actually got to say that), Gyarados has a pretty low Sp. Atk compared to Milotic's Sp. Def. Also, Dragon Dance is as good as useless since (considering you're using Thunder) the only stat to get a boost would be Speed, which is inconsecuential as it stands. (To put it in perspective, their base Speed is tied. This means that if Milotic goes first, HP Electric kills Gyarados. If Gyarados Dragon Dances first, Milotic still uses HP Electric to kill him).

Add to that Thunder's very shaky 70 accuracy, and even if you did manage to pull off a DD Thunder, you still have a high chance of missing. But even if you did hit, you probably wouldn't be able to dent to even half of it's HP considering your bad Sp. Atk and her good Sp. Def. But even if you did manage to dent it, she can just Recover the damage away and keep going as if nothing had happened. Also, she can put you to sleep with Hypnosis and proceed from there.

And, actually, even if he isn't using that horrible Thunder tactic, he'd have to rely on either Stone Edge or Earthquake for damage (considering that Bounce is a joke and his good STAB attacks are resisted by Milotic) both of which Milotic can shrug off with her overall bulk as long as their undoosted. Now, if he did decide to take the time to DD up, she'd take advantage of the setup and kill him with HP Electric. And Status moves don't work either as all they do is increase Milotic's Defense even higher (thanks to Marvel Scale) so you can't T-Wave or Toxic stall it either.

Actually, I've just argued myself into siding with Milotic on this matchup. As long as she carries Hidden Power (Electric), it's a sure fire victory for her. If she doesn't have the desired HP... well, then it becomes alot more difficult to predict a winner.