These are the villains from the story, We Met Again. All of these include the minions.
Many of the villains have an "Evil" rating in terms of how extreme a criminal they are by their mentality, persona etc. 
Rated from 1-10

1- Wannabe Villain Unsuccessful at Nearly Every Attempt 5-  Evil, Yet May Not Be Too Powerful, Or Intelligent  10- Evil and Murderous with a Sick, Sick Mentality

MASTERMINDS

AKA: The Dark Lord, He-Who-Must-Not-Be-Named, You-Know-Who
Alias: Tom Marvolo Riddle (Human form before evil)
Series: Harry Potter
Other Forms: Many
Evil Rating: 10

Tom Riddle was at once a wizard of high standards at Hogwarts. Soon, he had taken to being a wicked and  powerful Lord Voldemort. Voldemort takes delight in murdering innocent people for his own gain. He has also gathered many loyal supporters who are known as Death Eaters.
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Later on, Voldemort was overly defeated by Sakura in her fourth year, when magically thrown into the Forbidden Forest near the grounds of Hogwarts. There his body was weak and fragile, his body died while his evil spirit remained. Since Voldemort could only thrive within another, he possessed Renona's body. Once he had reformed himself, it was the beginning of a mission to destroy Harry and Sakura, the ones who defeated him and had the power to surpass him.

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AKA: Dark Raven, Lady Anbuanbu Karasu (meaning Dark Raven)  
Alias: Renona Kedevrahoshi
Series: None
 Other Forms: Animagus 

 Tom Riddle’s childhood lover. She separated from him a long time ago and moved to Japan. She was sent to a mental home where she reunited with Voldemort’s soul. She then became a zombie-like villain whom has the mission of murdering Sakura and Harry. Renona by herself was not evil, but her pure soul had intertwined with Voldemort's spiteful soul, forming a new kind of being within her. Her appearance changed as well, as she became a part of him. Her skin paled and her violet eyes glint red with malevolent contemplations. This is because Voldemort himself, had red eyes and pale skin in his original form. Karasu could only truly communicate with Voldemort’s soul through a skull though it looks more like she’s talking to herself.
She is also the one whom selects the minions to follow after her.
Karasu is also unable to actually, attack the Phoenix Fighters head on, because she still must gather enough physical strength. For this reason, she sends out evil minions to weaken the adversary for her.

 

 

HENCHMEN

Enemy: The Heartless
Alias: N/A
Battle: 1
Series: Kingdom Hearts
Other Forms: Where to begin...??
Defeated By: Sakura, using the Light card; Hermione, Harry and Ron, using the "Lumos"; Syaoran and Meiling 
Evil Rating: 3


Heartless are  beings without hearts derived from an unknown dimension. They are manipulated by Disney villains. If you want to know more, I suggest you play the game. :P

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Enemy: King Cold, Freeza, and Zarbon
Alias: N/A
Battle: 2
- See Dawn Dragonball
Opposition: Tien, Yamcha, Kurririn, Chaozu 
Defeated by: Sakura, killed Zarbon using the Mirror card; Trunks defeated both Cold and Freeza, using his sword and Ki blast
Evil Rating: Freeza-7 King Cold-5 Zarbon-6

King Cold was the king of planet Freeza, Freeza was his son. Freeza nearly destroyed the entire Saiyajin race, when destroying the planet Vegeta (where Saiyajins resided) with a single blast. 
Zarbon was Freeza's right-hand-man and also his most loyal servant.

 

 

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Enemy: Team Rocket (English Dub)
Alias: Jessie, James and Meowth, 
Battle: 3
Other Forms: Same body, too many different disguises to list
Defeated By: Hermione, using Wingardium Leviosa
Opposition: Ash, Misty and Brock 
(Satoshi, Kasumi, Takeshi)
Evil Rating: 1

Is this really even worth explaining? Really? 
Is it??