Death Battle X: Jewelpet Diana vs Discord
Dark Diamond Eyes Disharmony

It was a full decade since Jewelpet Diana first played the first Big Bad of the epic long-running anime Jewelpet (back in Season 1, which premiered in 2009). But now that the franchise has become stagnant (no thanks to Magical Change), she set out to help revive JP in the 2020s. Looking back on when she cast mind-control spells on humans to create friendship problems, she wondered if another villain did the same thing but had the mind control broken in a nanosecond, thus evaporating any lasting impact said villain left. Then she pulled out her Jewel Pod to check the Internet for said villain scheme, finding plot summaries of The Return Of Harmony.
"This villain...Discord...mind controlled the Mane Six of My Little Pony: Friendship is Magic, turning their personalities opposite to the Elements of Harmony each of them bore. Honesty, Generosity, Kindness, Laughter, Loyalty, and Magic (of Friendship). He made the bearer of Kindness cruel?!? UNFORGIVABLE! Also...Discord's mind control was over before it started. I'll show Discord that I played a much better villain!"
With this, Diana arrived at Discord's hedge maze the same moment the Mane Six did during their search for the Elements of Harmony gems which had petrified him in the past. Rainbow Dash walked up to the maze and said, "Dopey Discord forgot about these babies", flapping her wings. She then flew upwards. "I'll just do a quick fly over and we'll have the Elements in no time." Then her wings disappeared and she fell down. "My wings!" Fluttershy's wings soon followed.
Then Twilight's and Rarity's horns disappeared as well. They both bellowed, "My horn! Your horn! Our horns" before panicking.
Discord then teleported in, revealing that he snapped the wings and horns away. "You should see the looks on your faces!" He then made a trolling face.
Diana then told the Mane Six, "STOP! Without your wings or magical horns, you six are clearly no match for him. Leave!"
Dashie then replied, "What do you know? You don't wield the Elements of Harmony! What makes you any better than their wielders?!?"
As the Mane Six then tried to beat her down with their hooves, Diana either parried or dodged every single hit from them. Without their wings or horns, that was all they could do to her. She then knocked each of the Mane Six out stone cold with a single punch or kick. "That. The speed and strength you just witnessed is standard for my species, the Jewelpets." Then she turned towards Discord. "You, sir, are facing me, Jewelpet Diana. I'll be more fun to play with than those six ponies."
Discord replied, "Aww, I was going to turn their personalities opposite to the Elements of Harmony. But I'll take your word for it. I have prior knowledge of the Mane Six's strengths and weaknesses, but not yours. So let's have some fun!" Little did he know, prior knowledge of his opponents was the only reason why he ever defeated anything, and his lack of prior knowledge on Diana would be his downfall.
Diana then took up a pre-fighting pose. "Let's dance!"
FIGHT!

Discord then summoned monstrous stacks of apples. "In chess, the pawns go first!"
As the apple stacks approached Diana, she shouted "Dark Dark Diamond Slash Claw", pulled out her claws, and carved up the apple stacks one by one while avoiding and parrying their tackles and apple throws, including slicing up the thrown apples. Then she ripped out the last one's core and crushed it with her forepaw, extracting the apple juice. Turning her attention to Discord, she yelled "I'll split you in two" and did exactly that to him.
However, he immediately pulled himself together. "That won't cut it. How about some balloons?" Then he summoned some mean-faced balloons, most of which Diana popped with her claws when they tried to tackle her. However, one of them wrapped its string around her neck in an attempt to snap it. To break free, she cut the string with her claws, charged the balloon with Force Lightning (seriously, she can do this on her own show), grabbed the part of the string still attached to the balloon, and beat up Discord with the electrified balloon, electrocuting him. This electrifying beating only stopped when Discord's claw finger popped the balloon. Then Diana shot him directly with her Force Lightning, causing his chaos magic to go haywire so he couldn't just snap her out of the fight.
"Shocking, eh?", she quipped. She then had to use her Force Lightning again on swarms of mean-faced butterflies Discord then summoned. The lightning took all the butterflies out. Discord then tried to snap Diana away, but only ended up creating massive walls that closed in on her. She just scaled them with a wall jump and jumped above them before roundhouse kicking him to the ground.
"How about some chocolate rain?", Discord quipped before summoning a pink raincloud that poured out explosive chocolate milk. Avoiding all the explosive chocolate milk, Diana jumped high and used her telekinesis to throw the cloud into Discord's mouth, blowing him apart. However, he quickly pulled himself together.
Diana facepawed. "Why won't you die?!?"
Discord replied, "Chaos magic, son. It flips the laws of physics and mortality." He then materialized shackles onto Diana's forepaws.
As Diana looked at the shackles and whispered "Optic Blast" in response, her eyes glowed yellow and shot a yellow laser beam that vaporized the shackles' chains. After taking off the shackles and throwing them at Discord's head, Diana shot both his shoulders with more Optic Blasts, staggering him. When he was done reeling, Discord dropped a mountain above her, only for her to briefly grow giant, catch the mountain, and crush him with it. As Discord reformed and exploded the mountain, he was shocked to see the now normal-sized Diana floating in the air, bellowing "Dark Dark Diamond Eyes Power" in front of a massive purple vortex background, and massive yellow eyes flashing a bright light with her in the middle.
"MY EYES!" After rubbing his eyes from the light flash, Discord looked at both his arms and saw dark purple paw prints on them: The sign of Diana's curse. In addition, the curse made him glow purple. "What does this mean?" He then tried to snap Diana away. "Why isn't my chaos magic working?!?"
"Under my spell, you will be orderly and never use your chaos magic again!" Diana then pulled out her Jewel Stick, while Discord grabbed a nearby wooden staff in response. The two combatants then began to swing their weapons at each other. Discord was so dependent on his chaos magic that he never bothered to take up martial arts, which bit him hard. His strikes were all focused on brute force and not accuracy. As he flailed the staff around, Diana either parried or dodged every single blow before disarming him, stealing the staff, giving him a massive beating with both it and her own Jewel Stick, and launching him into a wall. Without his magic, he was physically weak enough to be easily restrained by a random bystander. Then Diana yelled "Dark Dark Diamond Roundhouse Kick!" For the final blow, she leapt at Discord and performed a much more powerful roundhouse kick. To counter this, Discord got up and punched her in the leg with his right fist so hard that the combined force of both his punch and her kick created a massive rainbow-colored shockwave that engulfed Equestria, undoing every effect of Discord's chaos magic.
The kick was so hard that Discord fell back to the floor and his right arm was obliterated upon contact with Diana's leg. He then snapped his fingers with his left arm in an attempt to restore his right one, but Diana's curse still prevented him from doing so. "Impossible...I'm the Spirit of Chaos and Disharmony! Only the Elements of Harmony can defeat me!"
Diana then jumped onto Discord again. "Darling, you have no idea what's possible! Playtime's over!" She then stabbed him in the head with her Jewel Stick, causing him to explode in a massive ball of light and leave no body or soul behind.

KO!
After the explosion of light cleared, Diana winked while raising a fist above her head. "I did it! Going for the head, I put a decisive end to one of Equestria's greatest threats before he could cause any more trouble! Looks like Diana was the real spirit of chaos here!"

Back at Canterlot Castle, Princess Celestia announced "Welcome Diana, the magical cat who stood up to Discord and destroyed him completely, something we never thought was possible, for the Elements of Harmony were only able to seal him away instead of vaporizing him!" Diana then happily walked across the castle's massive red carpet with guards playing trumpets to both sides of her. Eventually, she reached a stained glass window depicting her taking away Discord's chaos magic, roundhouse kicking him, and finally lobotomizing him with her Jewel Stick.
Diana then said "Thank you for congratulating me."
"You're welcome. If Equestria is ever threatened again, I will count on you and your Jewelpet species instead of the untrained Element bearers to save the day." Celestia then gave Diana a medal to wear around her neck.
Word of Diana's victory over Discord then spread across Equestria. All of Equestria's most infamous evildoers then gave up on their schemes out of fear that Diana and her fellow Jewelpets would destroy them even harder than she did Discord. Also, Equestria was ready to accept the idea of Jewelpets and ponies living together in harmony.
THE END
Author's Note
Yes, a possible Jewelpet season in the 2020s revival could be My Little Jewelpet. Possible others include Jewelpet: Devil Trigger and Marvel Jewelpet.