Pogiforce-14 said:
But I'm referring to Swords Dance. :\ I don't want belly drum since it halves your HP, and I can't afford to replace two moves on Chelsea since she needs all of the other three. :\
Halving your HP isn't that bad if you can activate a Salac Berry when the opponent can't KO half your HP is one hit.
If you used DD, you'll be able to KO frail, speedy sweepers, as frostweaver said. If you use SD, you'll be able to KO things with moderate defences.
For example, if you use DD, then Earthquake a Tyranitar, you'll do about 80% damage, but then likely be KOed by Rock Slide. If you use SD, then Earthquake a Tyranitar, you'll likely KO it. But if you face something like Jolteon or Alakazam, it'll likely OHKO you. DD will allow you to OHKO Alakazam and Jolteon, though.
I based my calculations on a Tyranitar with maxed Speed and Attack -- no EVs in Defence. The same goes for Charizard (Adamant, maxed Attack and Speed EVs).
It's mostly a trade off, most teams lead with their quick sweeper, so if you can get rid of it, then its smooth sailing for Charizard with SD. Just don't put Charizard out first. If you use either move (SD or DD) and the opponent is relatively well-versed in the game, they'll just let you get one KO (or switch as the case may be), and then they'll get Charizard with whatever counter they need: a quick sweeper, or a tank.
It's a matter of preference. I suggest you try both out on NetBattle to see which one you like best. Personally, I like SD or BD.