Scott McCall and his pack of supernatural friends took on a lot of threats in Beacon Hills during the years The Vampire Diaries.
Vampires, in fact, were never a part of Teen Wolf during its run. Even magic was fairly limited. With vampires and witches a huge part of The Vampire Diaries, the villains would prove a serious challenge to what Scott and his friends were familiar with. They wouldn’t, however, have to concede defeat to everyone.
CAN DEFEAT: Rayna Cruz
Also known as the Huntress, Rayna is to vampires what the Argent family is to werewolves - to a degree. Unlike the Argents, Rayana has her own bit of magic, which makes her functionally immortal, her soul traveling to a new body in death.
Her hatred for vampires specifically means Rayna isn’t a threat to the McCall pack in particular, but they would certainly face off if Scott and his friends got in her way. It would likely be down to Stiles and Lydia to figure out if there was a way for Rayna’s next life to coincide with someone who could combat the bloodlust for vampires and make sure that’s where she ended up, but they could definitely do it.
CANNOT: Kai Parker
Consistently considered the evilest of Vampire Diaries villains, Kai is one formidable foe. It took all of his own family to lock him away in another dimension to keep him from hurting anyone.
Kai has too much fun as a villain. He doesn’t have just one goal, unlike most of the Teen Wolf villains. Instead, he just likes to do whatever he wants. That’s part of what makes him so dangerous. There’s also seemingly no humanity left in him. While Scott and his friends often rely on their own humanity to connect with some of the adversaries, like Peter Hale, of the Alpha Pack, and even the kitsune possessing Stiles, they can’t do that with Kai, and they would suffer for it.
CAN DEFEAT: Markos And The Travelers
The travelers are a group of descendants of witches. Cursed to never have a home, they spend their lives traveling - literally. They have also, however, learned to “travel” spiritually as well, allowing them to take over the bodies of others.
It doesn’t take long for Scott and his friends to realize that someone isn’t who they say they are thanks to their experiences with rage on the full moon and the kitsune that takes over Stiles. It wouldn’t take long for them to work out just what the travelers were up to and stop them.
CANNOT: Arcadius
As the world’s first psychic, Arcadius is so powerful that his own rage and grief creates a new dimension: Hell. He’s literally the devil and creates the Sirens, which Lydia would probably be fascinated by.
Arcadius, or Cade, is immortal, unable to be killed by conventional means. To be fair, he’s not impossible to defeat as Stefan is able to do it eventually by stabbing him with a dagger made from his own bones. If the McCall Pack is able to retrieve the dagger, they might be able to defeat him, but by then, he might have made contracts with half of the supernatural beings in Beacon Hills.
CAN DEFEAT: Isobel Flemming
A young woman obsessed with vampires, Isobel decides she doesn't want to be a mom, but she does want to be immortal. She runs away from her daughter as a teenager, and then her boyfriend as an adult, seeking out a vampire and making sure she gets herself turned into one.
Despite wanting to be immortal so badly, Isobel doesn’t really hone the skills she has as a vampire. The McCall Pack could easily stop whatever plan Isobel comes up with because she never embraced all parts of her supernatural life.
CANNOT: The Mikaelson Siblings
Klaus, Elijah, Rebekah, Kol, and Finn all do various deeds through The Vampire Diaries and spinoff series The Originals. They’re not really interested in being the bad guys, but sometimes their desires for power or revenge can put them on the opposing sides of the heroes they encounter. They are the most powerful vampires to exist, and only very specific items can destroy them.
Since the Mikaelsons are typically only villains as a means to an end, the McCall Pack probably wouldn’t even have to try to defeat them. Eventually, the two groups would likely end up being allies, just like Scott and the of the Hale family he encounters.
CAN DEFEAT: Dr. Maxfield
Wes Maxfield is all about figuring vampires out. He’s interested in what makes them tick and how to use them for his own ends.
Maxfield’s experimentation isn’t unlike that of the Dread Doctors in Teen Wolf. Unlike those villains, however, Maxfield is completely human. Despite his intelligence and scientific know-how, Maxfield is still an average human, and no match for the combined efforts of the pack, which includes werewolves, a werecoyote, a genius banshee, a hellhound, and plenty of smarter than average humans.
CANNOT: Qetsiyah
Qetsiyah isn’t a villain that the heroes defeat. She’s a villain who gives herself up when she’s completed her goals.
Qetsiyah is so singularly focused on her pain and her revenge on the man who wronged her that nothing else matters. She wants to punish Silas, not the entire world; she just doesn’t care much if other people end up hurt as a result of her pain. Her magic would be too strong for the McCall Pack to defeat. After all, she created the first immortal being. She would, however, be willing to team up with them to defeat someone else...
CAN DEFEAT: Silas
In another life, he is a witch. Thanks to manipulating Qetsiyah, who believed he loved her wholeheartedly, Silas becomes immortal. Silas has a lot of the same magical skills as Qetsiyah, but he’s not actually as powerful as her.
He’s manipulative, but he’s also overconfident. That overconfidence means he would definitely underestimate the McCall Pack’s commitment to saving their friends, their town, and anyone else Silas goes after.
CANNOT: Katherine Pierce
Katherine Pierce, or Katerina Petrova, is the ultimate survivor. There’s no line she isn’t willing to cross to save her own skin, even if she feels badly about it after the fact. Katherine just wants a chance to live her life without looking over her shoulder, and find her daughter - and for that, she’ll do anything.
Even throughout all of the trouble she causes in The Vampire Diaries, Katherine ultimately gets her wish. She even comes back from Hell and “the other side” multiple times. Even if the McCall Pack manage to defeat Katherine, she’d come back to haunt them.