X-Men vs. Street Fighter

In 1996, after some flirting with their characters as Secret Characters in both X-Men: Children of the Atom and Marvel Super Heroes, Capcom took the idea and ran with it, making a full-fledged crossover as X-Men vs. Street Fighter.

The game featured Cyclops, Wolverine, Rogue, Gambit, Storm, Sabretooth, Juggernaut and Magneto on the X-Men side, and Ryu, Ken, Chun-Li, Charlie, Dhalsim, Zangief, Cammy, M. Bison (Vega in Japan; "Dictator" for those who use the anti-region-confusion titles) and Akuma representing the Street Fighter franchise.

XSF introduced the tag team fighting dynamic which became the trademark for the Capcom vs. Whatever series of games: players choose two fighters and switch between them on the fly in the middle of battle, eschewing the usual two-round structure started by Street Fighter in favor of a one-round fight (the fight ends when both fighters on one team are eliminated). Each character has their own lifebar, and when switched out, the inactive fighter will heal some of the damage they've taken until called back into action. The game also allows players to use a deadly Double Super Combo where both fighters perform a Super Combo at the same time for massive damage.

The story was all but nonexistent, with the chosen team fighting their way through various team-ups before facing down Apocalypse in a slight genre change. After defeating Apocalypse, you fight against your tag partner using whatever character landed the final blow during the boss battle. So much for teamwork...

Followed in 1997 with Marvel Super Heroes vs. Street Fighter.

""Je suis le meilleur!" "La tournament est fini.""
 * A God Am I: M. Bison and Magneto's endings in X-Men vs. Street Fighter also have this. In the latter,
 * American Accents: Rogue's winquotes are written with Southern accents.
 * And I Must Scream: In Charlie's ending,
 * An Ice Person: Storm in some of her attacks.
 * Attract Mode
 * Badass Normal: Zangief.
 * Chun-Li's X-Men vs. Street Fighter ending has her being invited to join the X-Men. Ryu is also invited to join both the X-Men (in the aforementioned game) and the Avengers (in Marvel Super Heroes vs. Street Fighter), but politely declines both offers.
 * Big Bad: Apocalypse.
 * Bilingual Bonus: Some of Gambit's winquotes are written in French:

"BEHOLD! OPTIC BLAST!"
 * Blow You Away: Storm uses wind attacks as a few of her specials, and combines it with An Ice Person for one of her Supers.
 * Calling Your Attacks: You'd expect this with the Fighting Game characters, naturally. But it even extends to the Marvel Superheroes, among others.

"Sabretooth: This ain't no Street Fighter! You lose..."
 * The Cameo: Many characters from both universes make appearances in the endings and stages.
 * Combination Attack: Double Supers.
 * Deep South: Rogue, sugah.
 * Early-Bird Cameo: This game introduced Shadowloo-era Cammy before the Street Fighter Alpha series did.
 * Everything's Better with Spinning: Zangief.
 * Excuse Plot: Random... ahem... street fights due to the interdimensional rift.
 * I Just Want to Be Normal: In Rogue's ending,
 * Kamehame Hadoken: The second part of the trope's name comes from the version of the Shinkuu Hadouken, which is the best known of many, MANY, MANY instances.
 * Kick Chick: Chun-Li and Cammy.
 * Powered Armor: Apocalypse.
 * Ryu and Ken: Both of them and Akuma.
 * Shock and Awe: Storm's primary form of offense. Many other characters have at least one shock/stun move.
 * Shotoclone: Ryu, Ken, Cyclops and Akuma.
 * Shout-Out: Check the page.
 * Stripperific: In the ladies' side, Cammy. In the men's side, Zangief and Dhalsim.
 * Surprisingly Good English: Cammy and all Marvel characters are voiced by native English speakers.
 * Tag Team: It's the first game in the series which incorporates that, predating a lot of future games.
 * Take That:

""HYPER COMBO FINISH!""
 * There Is No Kill Like Overkill: