SmallvilleX: Evolution

SmallvilleX: Evolution is an ongoing Crossover Fanfic of Smallville and X-Men: Evolution by ben10987654321. This story is set during Smallville's season 3 and X-Men's season 2.

The story begins when the Kents are about to lose the farm after Clark's Red Kryptonite Binge in Metropolis. Lex Luthor is out of the country and is unable to buy the farm like he did in canon. Virgil Swann informs Charles Xavier of the situation and recommends inviting Clark Kent to the institute in Bayville.

Meanwhile Magneto and Sabertooth are in Smallville investigating the Kryptonite infected mutants. While most of them are too unstable for Magneto to use he is hoping at least one of them is a genuine x-gene mutant that can fight for his cause. He receives a tip from Dr. Essex at Belle Reve to observe Clark Kent, whom Essex believes is simply an extra powerful mutant.

What's notable about this crossover is the effort made to blend the two stories together. The backstories are fused together nicely and the threats are a mix of villains from both continuities. The author isn't afraid to use characters from other Superman/X-Men continuities if it helps the story.

Tropes used in SmallvilleX: Evolution include:

All Your Powers Combined: Clark has a version of Scott's optic blast, Juggernaut's strength and invulnerability, Pietro's speed, Logan's healing factor and enhanced sense of smell, plus super-hearing and x-ray vision. No wonder Magneto wants Clark on his side.
Beam-O-War: Scott's Optic Blasts vs Clark's Heat Vision. They tied until Kryptonite was used.
Breaking the Fourth Wall: Deadpool of course.
The Cameo: Spider-Man makes an appearance as well as a few members of his Rogues Gallery. The author has also stated that Deadpool will appear in the future.
Clark Kenting: Obviously, but puts more effort into making it plausible than canon.
Corrupt Corporate Executive: Lionel Luthor.
Crossover Ship: Clark/Rogue.
Demoted to Extra: Lex only makes one appearance, and that's just to explain why Chloe and Pete are in New York right before Christmas. He's out of the country for most of the series.
Distracted by the Sexy: Several characters experience this, particularly when Clark is shirtless.
Don't Explain the Joke: Often the author will add asides to explain completely obvious comments, innuendo, and jokes.
Fridge Logic: In-universe. When Magneto discovers Clark's weakness he observes that it makes no sense for an invulnerable mutant to succumb to space rocks. He knows he's missing something, but doesn't make the alien connection.
Gambit Pileup: Headed this way. We've got Xavier's plans for peace, Magneto's plans for mutant domination, Lionel's plans to exploit mutants, Mystique's own agenda, Stryker's mutant vs mutant plan, Trask's Sentinel project, Apocalypse's plan to take over, and Jor-El's plan to do God knows what.
Kryptonite Is Everywhere: Even when Clark is 1000 miles away from Smallville the Green Rocks just will not leave him alone.
Mama Bear: Mystique is like this with Alicia, whom she adopted for legal reasons but eventually cares for genuinely.
Manipulative Bastard: Red K!Clark arranges a fight between the X-Men and himself+the brotherhood simply to get Rogue to absorb Alicia and see how she knew about the Red K.
Occam's Razor: Lampshaded. Rogue's power doesn't work on Clark simply because he's an alien.
Oh Crikey: Pyro's response to seeing Colossus beaten by Clark.
Psychic Block Defense: Telepaths cant understand Clark's alien thoughts, as if they are spoken in a foreign language.
Red Herring: During the search for missing Jean some Smallville fans will notice Clark's sudden fatigue and expect him to develop super-breath like when this happened in canon. However it was just a sliver of Kryptonite doing that and no new powers in that chapter.
Shipper on Deck: Kitty encourages Rogue and Clark to get together.
Spanner in the Works: Clark's super-hearing lets him detect Mystique despite her enhanced shapeshifting, which prevents her from executing her plans to infiltrate the institute.
What Happened to the Mouse??: Since Clark left Smallville, who's fighting the Monster of the Week?
What Kind of Lame Power Is Heart, Anyway?: Spider-Man feels his powers are this in comparison to Clark's.

"I need better powers."

The Worf Effect: Clark brings down Beast, Storm, and Logan in minutes by himself while under Red Kryptonite, just to show off how much the X-Men are screwed without Green Kryptonite.