Imagine this... Xemnas vs. Celestia, Saix vs. Luna, Roxas vs. Dash, Demyx vs. Twilight, Axel vs. Rarity, Luxord vs. AJ, Xaldin vs. Fluttershy, Xigbar vs. Pinkie. Could it be called a matching set of villains?

2793271 well Celestia is doomed , the other ponies except Twilight , Pinkie and Fluttershy as well

2793271 I don't see how Axel vs Rarity or Xaldin vs Fluttershy would work.

2793335 Rarity tosses pillows at Axel, Axel burns them (creation vs. destruction)
Xaldin sends Beast at Fluttershy, she stares him
It's just that most of them have opposite forces... like harmony vs. anti-harmony

2793421 i wanna see the xigbar vs. pinkie pie fight!and i would like the cmc verses the main three(sora,donald, and goofy.)

Xemnas vs Celestia: Can you spare a heart? Also, infinite Ethereal Blades are go.
Saix vs Luna: He grows stronger and more angry as the moon grows full. At the same time, it's the only thing that causes him to feel emotion. I imagine he'll demand a heart and when she's confused chase her around.
Roxas vs Dash: Roxas can move so quickly a lens flare is right behind him when he moves. He harnesses light to move quickly. While this doesn't put him at light speed, he also has the light death days as well as death twirls.
Demyx vs Twilight: Demyx surrenders.
Axel vs Rarity: BURN, BABY!
Luxord vs AJ: They truce and play card games.
Xaldin vs Fluttershy: Xaldin flies away on his wind dragon and shreds everything in sight.
Xigbar vs Pinkie: All things against Pinkie start to disobey the laws of physics. Xigbar already does, so I imagine it'll end in a draw.

I don't think Axel would fight em...Larxene would fit more in place. And whilst Roxas and dash fighting would be interesting..aside from a misunderstanding, i can't imagine them doing so. And even then, Roxas wouldn't support the others..except maybe Axel

2795579 Larxene's element is... pain, so the opposite to it would be healing; she could probably be an enemy to somepony with plant/healing powers

2797229 Still..Roxas and Axel aren't bad guys....How about Marluxia? He is an ursurper within the Organization...Wanting the power to himself.. Greed..Vs Generosity..

2797962 You're right. Marluxia is hard to assign to any element alone, though, he probably has several kinds of evil at once.

2799224 Rarity would fit him best..Dash i..really can't say..I imagine it would be more of their characters instead of their powers or evils.. but i legitimately can't think of one for Dash..