Think about your closest friends. If you know them well enough, you also know their strengths and weaknesses. You know how they think, how they react, how they tick. You trust them to know the same about you, too. You might even trust them enough to let them fix your car—but not drive it. Hell would freeze over before you let them drive it.
In action oriented stories, two characters who are friends will work with each other during combat. Often this will present the image of Back-to-Back Badasses. If one person is big and the other short, the big guy will use brute strength and the short guy will use finesse. Maybe the big guy will clasp hands with the short guy and fling him around as though he was a weapon. Or the big guy will use the short guyas a projectile.
But no matter what, they will fight in tandem. They will watch each other's back. There is something genuinely satisfying about watching the heroes take out a room full of bad guys by working together. This isn't always limited to merely two people, as often the Five-Man Band can emulate even more varieties of combat.
Characters who tend to do this are The Hero and The Lancer, while The Big Guy can alternate between any of them. The Smart Guy takes down the Elite Mooks with precision Pressure Points and The Chick provides long-distance support as archer. This is one reason why the Badass Army tend to do so well even when outnumbered. Even a mismatched Action Duo can be Bash Brothers with enough bonding/training.
It is not uncommon in certain stories to have two separate badasses who come together, spend some time trying to kill each other only to eventually turn their skills onto the hapless enemy who happens to piss them both off.
If the "brothers" are actually related by blood, it's a Sibling Team. A combative inversion is Fearful Symmetry. In a fantasy setting, they might be a Sword and Sorcerer. Not to be confused with the Smash Brothers who are, well, Super. The romantic version is the Battle Couple. And finally, a female duo may well be Lovely Angels.
Compare Red Oni, Blue Oni, Ryu and Ken, and Sword and Sorcerer.
The name comes from the world of sports, where it refers to a pair of great players who end up on the same team. The first use of the term was in baseball, where Jose Canseco and Mark McGwire formed a dangerous duo for the late-1980s-early-1990s Oakland A's. It has since spread to other players and sports.
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Berserk has a few moments like this in later arcs, with Guts smashing headlong into the Monster of the Week while Serpico leaps around taking care of the Mooks.
While they're not really close friends, one episode of Bleach had Chad and Uryu facing off against two foes. Originally, they were getting beat up hard. That is, until Uryu opted to switch opponents with Chad, seeing Chad's slow but strong style better on Uryu's opponet, and Uryu weak but fast style on Chad's.
Before the advent of Rukia and The Call Knows Where You Live and Ichigo turning into this unstoppable level-grinding machine, Ichigo and Chad also went bully hunting like this. They agreed years ago that if it wasn't okay to get in fights on their own behalves (and being redheaded and half-Mexican, respectively, they're major targets) they would always fight to protect each other. It's very sweet. Chad has spent the last two hundred chapters trying to be strong enough to keep this promise again. No dice.
Dragon Ball Z: Gohan and Krillin are the best of friends and greatest examples of bash brothers (though, ironically, Krillin is close friends with Gohan's father and is more of an extended uncle to Gohan). After the seven year time skip, the next generation of warriors Goten and Trunks are the newest set of bash brothers to the show.
Burter and Jeice are implied to be this, being the only members of the Ginyu Force who fight together rather than one-on-one. Unfortunately for them, their only on-screen fight is against Goku, who's way out of their league.
Goku and Vegeta play with this, but mostly in the movies and especially the Majin Buu saga.
In Gintama, this happens mostly during the serious episodes. Usually, Kagura and Shinpachi team up in the serious story arcs to deal with Mooks and the occasional Elite Mook.
The Benizakura Arc has Gintoki and Zura Katsura in a Back-to-Back Badasses moment, fighting against space pirates hired by Takasugi and then declaring war on Takasugi with the exact same words and in the exact same manner.
Kira and Athrun from Gundam SEED do this several times, coordinating their attacks and defenses to the point of near-telepathy.
From Harlem Beat, we have Naruse-Sawamura duo both in their streetball and highschool team.
In Hunter × Hunter it was said that two members of the Genei Ryodan (Uvogin and Nobunaga Hazama) had this kind of relationship. They were at their strongest when they fought large groups of enemies together, though Uvogin would never admit it.
In the second last episode of Kotetsushin Jeeg, both Hiroshi Shiba (the original Jeeg pilot) and Kenji Kusanagi (the sequel's new pilot) are finally given the chance to both transform into their respective Super Robots, and what follows is an epic, epic double-teaming brawl.
Nagi and his team the Ala Rubra in Mahou Sensei Negima! fought like this. Negi and Kotaro have been developing a style like this since entering the colosseum as a team.
Mazinger Z has Kouji and Boss. They begin at odds with each other but quickly they become good friends and fight together; Great Mazinger has Tetsuya and boss, and later in the series, Tetsuya and Kouji; UFO Robo Grendizer gave us Kouji and Duke; And finally Mazinkaiser showed more examples of how devastating Kouji and Tetsuya are when they are fighting together.
Subverted in Naruto. It looks like Naruto and Sasuke are building into this, but then Sasuke pulled a Face Heel Turn.
As of Shippuden, Naruto has developed into this with Killer B, who is also this with A / the Raikage. It turns out they're not actually related - A adopted Bee because he was badass enough for their combat styles to mesh.
Ino-Shikamaru-Chouji is a better fit. They've been best friends for so long (since before they became ninjas), Chouji is able to pick up Shikamaru's strategies and prepare well before anyone else, Shikamaru knows just how to set up Ino's powers, and likewise Ino knows how to cover Chouji's weak points. By the time of the 4th Ninja World War, the trio's practically invincible.
The Ino-Shika-Cho trio even extends into their family. It's actually a tradition for three of the current generation to be put into a team together with a Sarutobi as their sensei.
And more recently, Kinkaku and Ginkaku. The two dead shinobi who survived being eaten by the Kyuubi for two weeks!
In One Piece, Zoro and Sanji are somewhat like this. They may bicker in the midst of battle and occasionally attack each other, but once they work together (as shown in the Davy Jones games), they are near invincible.
And as of chapter 572 we've had Luffy and Ace.
The entirety of the Straw Hat Pirates are very capable at working together against foes. This aspect was heavily portrayed during the events at Thriller Bark and the Sabaody Archipelago.
Ranma ½ has a antagonistic version of this as a Villain of the Week arc. Azusa Shiratori and Mikado Sanzenine are masters of Martial Arts Figure Skating, a team known as the Golden Pair for their combined skill and excellent teamwork. Outside of combat, however, the two don't get on too well, as Mikado finds Azusa's kleptomania and ditzy antics annoying, while Azusa has the personality of a Spoiled Brat and is quite willing to beat on Mikado if he interferes with her antics (giving back something she stole from a pretty girl, or chasing girls when he should be practicing). In fact, she's ultimately the one who beats Mikado, causing them to lose.
Perhaps to highlight their Belligerent Sexual Tension, Ranma and Akane keep swinging between playing this straight and averting it. While they played it perfectly straight in the Martial Arts Figure Skating story, most if not all of their subsequent 'team battles' had them getting in each other's way and forgetting to pay attention to their enemies to squabble with each other (often over the fact Akane is Overshadowed by Awesome compared to Ranma and Can't Catch Up, yet refuses to admit this)... though, inevitably, they would pull together (if only after having been beaten once) and manage to pull off a victory, though their opponent would frequently come close to victory by taking advantage of their bickering.
Yu-Gi-Oh! had two pairs: The Paradox Brothers from the Duelist Kingdom arc and Lumis/Umbra from the Battle City arc. Joey and Yugi are this in their various tag team duels (heck, even their Dark Magician and Flame Swordsman show signs of it); a major problem in the Lumis/Umbra duel is Yugi and Kaiba's inability to pull this trope off.
Yusuke and Kuwabara from YuYu Hakusho were a more heroic version.
This following upon several years of Kuwabara incessantly returning to challenge Yusuke to fights and getting his clock soundly cleaned. Yusuke has been known to do this with other members of his team, as well. Once very briefly with Hiei.
Sena and Monta from Eyeshield 21 are the best (respectively) runningback and wide receiver in Japan, best friends, and the keys to Deimon's offensive power. Needless to say, some of the Devilbat's best plays involve the two working together.
Of course, there are also the Ha-Ha Brothers who show signs of this, though they're a triple package. The moves they used in their first game, and continue to use, sink the "bash" part rather well. A more conventional example would be Tetsuma and The Kid of the Wild Gunmen, showing how epic their teamwork was in their first appearance.
Similar examples would be Taka and Yamato of the Teikoku Alexanders (another runningback/reciever duo), and the lethal three way combo of Takami (quarterback), Shin (linebacker/runningback), and Sakuraba (reciever) of the Ojou White Knights. The last three are especially interesting as Sakuraba and Shin, and Sakuraba and Takami are Bash Brothers by themselves; when their plays begin to intersect it simply becomes more of a problem for the other team. For a literal example, there's the Sibling Team of Agon and Unsui of the Shinryuuji Nagas.
Despite being the leaders on the opposite spectrum for talent, Agon and Hiruma are an effective combination. Agon who runs on pure reaction is complemented by Hiruma who runs on pure mental ability. Despite their hatred for each other, they work extremely well together.
The title characters of Tiger & Bunny become this once Kotetsu/Wild Tiger successfully wins Barnaby/"Bunny"'s trust in him.
In Air Gear, the original members of the Sleeping Forest all seem to fight in duos in ways that support each others' styles. Probably part of why they're one of the greatest Storm Rider teams in existence.
Averted, lampshaded, then played straight by these two, actually, in the World's Finest maxiseries; the first time they meet with the explicit purpose of working together, they're at a function as Bruce and Clark when the guest of honor, a world-famous plastic surgeon is kidnapped. They split up and both go after the kidnapper, which so spooks the hostage that he runs out into the street and gets himself killed. When they compare notes they both observe that this happened because they didn't work together. The rest of the series is about their annual meetings to honor their failure and learn to work together until they're working as a well-oiled machine. Some of their guilt is mitigated when they learn at the end of the maxiseries that said hostage was actually the surgeon's body double who had kidnapped and replaced the real man after giving him amnesia in an attempt to steal his fortune. The real reason he was so spooked was because he was afraid that Batman and Superman would expose his scheme.
In the X-Men, Colossus and Wolverine have the "Fastball Special" (sometimes called for with "Hey bub..two words"), which basically involves Colossus throwing Wolverine at an opponent. Other characters inside and outside of Marvel have occasionally borrowed the move. Basically any combo of a character with Super Strength and one with an Absurdly Sharp Blade or six can do this.
Any combination of Wolverine, Colossus and/or Nightcrawler.
In the extremely rare occasions that they're seeing eye to eye, Cyclops and Wolverine can do this quite well, though they end up as Red Oni, Blue Oni much more often.
Power Man and Iron Fist are perhaps one of Marvel's best examples of this trope in action: Luke is a Made of IronBoisterous Bruiser and Danny is Weak, but Skilled with some elements of Lightning Bruiser. Ever since they were paired up for roughly two decades worth of comics they were ALWAYS seen together, until Luke got picked as one of Brian Bendis' favorite characters and appeared more often without him. The duo was reunited when Danny joined the New Avengers, of which Cage had become the leader.
Spider-Man and Daredevil. The two have teamed up many times and they are best buddies. It helps that they both share a number of villains. (Their first ever collaboration was against an evil hypnotist who couldn't affect the blind Daredevil but made Spidey beat him up for a while.)
And their shared enemies the Enforcers featured Ox and Fancy Dan, who would often tag team enemies with their astounding strength and martial arts skills, respectively. Later additions Hammer Harrison and Snake Marston would do much the same.
Marvel's Zapata Brothers are Mexican wrestlers, so it's only to be expected that they have an array of team-up moves. They also enjoy high-fiving during melees and switching out as if they were in a tag team match.
Sam & Max: Freelance Police aren't fighters per se, but if there are doors to bust down and bad guys with lead deficiency, they'll deliver the damage together. Moreso in the comics, but they get rare moments in the video games, too.
Astérix and Obelix always team up together to beat up a bunch of Roman soldiers. While sometimes they have the village to fight with them, most of the time it's the two of them (and Dogmatix).
In Star Wars: Legacy, Cade Skywalker and Jariah Syn are this throughout his pirate and bounty hunting days, though on Jedi stuff Cade's fellow Padawan Shado Vao sometimes takes the role. Imperial Knights Antares Draco and Ganner Krieg almost always fight as an in-sync duo.
The 2009 Star Trek Film, when Kirk and Spock beam onto the Narada and start shooting up everything in sight.
In Black Hawk Down and Real Life, the two Medal of Honor winning snipers, Randy Shughart and Gary Gordon live, breathe, and die this trope. From their hilarious-slash-Tear Jerker Chess game, which they never manage to finish, to their exchange of looks before they both deploy to aid the downed Night Stalker, the film makes the friendship of the two remarkably clear for two fairly minor characters.
Any cooperative combat in the Star Wars prequels, especially between Masters and their Padawans. Obi-Wan and Qui-Gon against Darth Maul in Episode 1 are the best example. It is because of the same thing with Obi-Wan and Anakin in Episode 3 that turned their climactic duel into a sort of Fearful Symmetry.
Probably the best moment of Spider-Man 3, with Spider-Man and Harry.
Fulton Reed and Dean Portman in D2: The Mighty Ducks were explicitly called "the Bash Brothers." Also affectionately called "Enforcers."
An enforcer is actually an unofficial role on an ice hockey team, not a title. Their job is to play dirty and violent.
Aragorn and Gimli did a fine example of this in The Two Towers. Needing to give a gate some time to be repaired, Aragorn and Gimli did a flying leap onto the ramp and proceeded to fight off an entire legion of Uruk-hai. One of the best sequences of many impressive ones in the trilogy.
One of the tag teams in Nacho Libre did a lot of this (also incorporating high-fives and the like), apparently being twin brothers.
One of the central motifs of Heroic Bloodshed movies like A Better Tomorrow, The Killer and Hard Boiled is two characters, usually Blood Brothers as well as Bash Brothers, doing this.
Any of the Rush Hour movies with Chris Tucker and Jackie Chan.
Also the movies with Italian actors Bud Spencer and Terence Hill.
In The Chronicles of Riddick, Riddick and Kyra are a rare opposite sex version of this, once they stop fighting each other. The Crematoria sequence showcases it nicely.
Pirates of the Caribbean had this in various sequences, but the most pure form was when Will was trying to free Jack from the noose and they raced to the castle edge. Subverted in that they taken down plenty of soldiers between the two of them, but sheer numbers and guns outweighed their ability to finish their job.
300 outlines this in particular when discussing their tactics. The individual Spartan is superior to the individual Persian soldier, but their sheer numbers would overwhelm them in any situation except for the bottleneck position they chose to defend. Even then, only because each Spartan defended the one next to them that they created a near impenetrable line... of course, they don't always follow this rule, often preferring the Rule Of Cool and breaking the line for slow-motion individual brawls.
In Iron Man 2, Tony and Rhodey do this after finally settling their differences.
In The Devil's Rejects, a pair of bounty hunters called the Unholy Two are hired to track down and capture the Ax Crazy Firefly clan. They actually succeed and disappear afterwards with no repercussions.
Pretty much everyone in The Avengers. Black Widow and Hawkeye constantly once Hawkeye is back on the Avengers' side, Thor and Captain America, and Thor and the Hulk are particularly notable.
Drizzt Do'Urden and Artemis Entreri can operate like this, much to their mutual displeasure.
They're both highly skilled dual-wielders who independently developed extremely similar fighting styles...And it took them about five minutes of conversation for each to recognize the other as what he could have been. Both don't like what they see in the other person, especially when compared to what they see as their strong points. However, if they must cooperate, they slaughter entire groups of who they're against. Often fighting back-to-back and continually moving, and with one setting up an opening for the other to exploit a second later, and it's mentioned that they move so much in sync that it's tough to tell who's who or who's doing what.
Rodrigo Belmonte and Ammar ibn Khairan in Guy Gavriel Kay's The Lions Of Al Rassan literally fight back to back at one point, taking out some mooks to prove their awesomeness. Later, they're forced to fight one another as the champions of Expys of the Muslims and Christians in medieval Spain.
In Eragon, Eragon and Murtagh shared the field of battle many times early in the series and developed a bond as strong as brotherhood. It wasn't too surprising when they turned out to actually be brothers.
A more consistent example is Eragon and Arya. It's even explicitly stated that they're the other's perfect shield mate.
Sherlock Holmes and Dr. Watson are a classic case. Just check out the "Awesome" page for the series and note the examples falling under "Holmes & Watson".
Harry Dresden and Karrin Murphy become this, because Harry is a magic nerd who, despite his Memetic Sex God page, really has no idea at all about women. It's lampshaded as pretty sad several times throughout the series.
The Alphas: they're a pack of wolves with human-level intelligence. Be. Afraid.
Harry and Thomas Raith become this. like the Eragon example, it shouldn't be that much of a surprise that they're half-brothers.
Thomas and Lara Raith in full vamped-out mode cut through an army of super-ghouls like chaff. Harry describes them as matched parts of a force of nature, their stand all the more beautiful and awe-inspiring for being totally hopeless.
The concept of "parabatai" in The Mortal Instruments and Infernal Devices is absolutely this trope. The latter series has the clearest example- Will Herondale and Jem Carstairs- but Jace Herondale/Lightwood and Alec Lightwood of the former also fit.
Life On Mars- Sam Tyler and Gene Hunt have been known to achieve this on occasion.
On occasion? Tandem desk-leaping & sychronized punching.
The A-Team. Very much so. Hannibal knows the strengths and weaknesses of each of the other three team members, and knows exactly how to best use their strengths and minimize their weaknesses. Different as they may be, when they all fight together, it's a bad day for slimeballs everywhere.
Face and Murdock especially seem to be this. They have a very effective tag-team fighting style.
Doubly so for Murdock and B.A. They usually drive each other nuts, but together they are a force of nature.
The Stargate Atlantis episode "Midway." A horde of Wraith decide to storm Earth, and slaughter most of Midway station staff. Who's gonna stop 'em? Two guys named Teal'c and Ronon Dex. The opening featured the two of them trying to beat each other to death, it was simply amazing to watch them turn their combined badassery on the hapless Wraith.
NCIS: LA. G. Callen and Sam Hanna always have each other's back. They bicker sometimes and have a friendly rivalry, but always come through for one another.
It's always a treat to watch the four team members of Stargate SG-1 combine to unleash maximum badassness on their enemies.
Norse Mythology: In the many stories where they weren't beating the crap out of each other, Thor and Loki often wandered the countryside together, looking for asses to kick. A relationship thought by some to be evocative of Lightning and Fire. Loki also had a great time tag-teaming with his blood-brother, Odin.
Even more in Haloid's spiritual sequel, Dead Fantasy, most notably with Ayane/Kasumi and Yuna/Rikku, but really all the characters did this constantly.
To a degree with a well-trained military unit. Most special forces teams are trained this way, covering what their buddies can't. No tossing each other around though as far as I know.
Fighter aircraft usually fight in pairs, the wingman covering the leader.
And also operate in pairs of pairs - a common formation for fighter aircraft (at least in World War II) has four aircraft forming a flight, in which there are two elements, each with two aircraft constantly covering each other, and each element covering the other. Two well-known formations of this type are the American Finger Four (origin of the name: hold out your hand, fingers together. If each fingernail represents one aircraft, that shape is basically a Finger Four formation) and the German Schwarm (basically identical, just appeared earlier on). The Germans' early adoption of this sort of formation led to some early, easy victories against the Royal Air Force.
Every pro wrestling tag team ever, but some tandems exemplify the big guy/little guy dichotomy particularly well: Batista and Rey Mysterio Jr (at least until Batista's Face Heel Turn), Rikishi and Scotty 2 Hotty, and Jesse and Festus to name a few.
Edge and Christian, they don't exemplify big guy-little guy so well, but they do have the camraderie down to an art, Truth in Television on that I guess...
Dungeons & Dragons: in the typical Fighter-Rogue-Wizard-Cleric party, the Fighter and Rogue fight most efficiently together in a manner similar to this - the fighter directing the battle and drawing the attention of his targets while the rogue tumbles into an advantageous position to deal massive Sneak Attack damage.
Magic: The Gathering would frequently set up two cards that are designed to complement each other and other cards controlled by the player in this way. The most pure form is the Brothers Yamazaki from the Kamigawa set, in which the one Legendary per name on the field rule doesn't apply to them and they give each other a major boost when together.
Star Wars Miniatures has some pairs of characters who have Synergy (combat bonuses) or Rapport (cost discounts) when used together. There is also a tournament format called "Dynamic Duo", in which players select only two characters for their squad, who must together cost exactly 100 points.
Warhammer 40,000 has a few unit combinations that compliment each others' skills very effectively. Scout Bikers and Terminators in a Space Marine army, for instance; the Scouts have teleport homers that patch up the Terminators' lack of mobility by dropping them on the enemy on a spot that moves very quickly, the Terminators make up for the Scouts' lack of durability and close combat prowess, everyone wins. Except for the poor Tau on the other side of the field that just got a new orifice to defecate through.
Mario Kart: Double Dash!! is built on doing this in a racing game. Each kart has two racers: a driver and a support. They function as one when one person is playing, but if two players decide to go co-op on one kart, racing ability is expanded with one player driving and both players mashing the control stick to achieve miniturbos. The first player can pass items he gets back to the second player, who focuses on using them and can also punch left and right to move the kart a little in those directions to dodge things, attack other players, and steal items.
Fire Emblem: Awakening allows the player to make any two characters into Bash Brothers with the Pair Up / Dual system. The more often you do it, or they even stand next to each other, the more often they'll either defend each other from enemy attacks preventing all damage, or double team a enemy offensively. Do it often enough between a male and female duo and they'll eventually get married.
The multiplayer campaign options of the Gears of War series features a storyline that kept the main character Marcus with his buddy Dom. A big part of the gameplay involves you yelling at your co-op buddy to cover you while you move forward.
Halo 3 has the Arbiter fighting next to Master Chief for much of the game in single player, and all of the game in co-op. You can even include a pair of unique, though undeveloped Elite characters online and play four person co-op. This is in contrast to Halo 2 where the game has no in-universe reason why a second Spartan accompanies you on the campaign.
Also from Halo, the Hunters always come in pairs. In most of the games, they are identically equipped and colored. Halo 3: ODST changes this: Hunters can either come in the standard blue armor and [[BFG fuel rod cannon]] that they had in Halo 3 or in gold armor and with an explosive fuel rod gun like all Hunters had in Halo: Combat Evolved.
Devil May Cry: Dante and Vergil against Arkham. They even say "Jackpot" at the same time.
Bio Shock 2: As Subject Delta, you are probably the biggest, meanest, and most well armed and armored thing that ever walked through the halls of Rapture. In the last level you get the Eleventh Hour Superpower plasmid that is rightfully described as "It's Bring Your Daughter To Work Day". Together with Eleanor even hordes of Brutes, Alphas, and Houdinis don't last against you for more than a few seconds.
AND in Super Mario RPG, Bowser and Mario can do this with some of the Koopa King's weapons being various gloves used to throw Mario himself.
In Mario And Luigi Superstar Saga, Popple and Bowser (as "Rookie") do this with new team attacks during their second battle with the Mario Bros. One of the attacks even involves Bowser throwing Popple.
Sacrifice has the Hachimen, even though it's not a fighting game, they're exactly the same thing.
World of Warcraft has a few of these as bosses, forcing the players to defeat two enemies working together, effectively turning them into one meta-boss encounter. The Eredar Twins in Sunwell Plateau and more memorably the Twin Emperors of Ahn'Qiraj are boss encounters with two powerful enemies, the battle commonly known as the Bug Trio of Ahn'Qiraj, as the name implies, pits three enemies against the players, the final battle of the Death Knight wing of Naxxramas is against the Four Horsemen-Sir Zeliek, Thane Korthazz, Lady Blameux, and Baron Rivendare (who replaced Highlord Mograine), and from the Crimson Halls of Icecrown Citadel, the Blood Prince Council (super upgraded and revived versions of Blood-Princes Valanar, Taldaram, and Keleseth).
Cataclysm's Blackwing Descent raid instance has you fighting the reanimated Nefarian after he also brings his sister Onyxia back to life. Just to drive the point home, they attack twice as fast by just being in close proximity to eachother.
One of the attract cinemas for Tekken 5 shows Kazuya and Heihachi battling an army of Jack cyborgs, until Kazuya throws an exhausted Heihachi their way to secure his escape.
Sonic and Tails have been doing this since Sonic 2, and Sonic and Knuckles often invoke this when they get over their differences and work together, likewise for Sonic and Shadow on occasion. Meanwhile, Amy and Cream often act as BashSmashSisters.
Sonic & Tails are back to their Bash Brother antics in Sonic 4: Episode 2, and aside from the classic Tails-carrying-Sonic tactic, they can create a dual spin dash.
Some sections of Half-Life 2 and Episode 2 and nearly all of HL2: Episode 1 have Gordon and Alyx working in tandem.
In Banjo-Kazooie, the titular pair invoke this trope despite one-half of the duo being female; they perform almost all their moves by working together, and are actually literally inseparable all throughout the first game.
Yuri takes Soap's place in the later missions of Modern Warfare 3 after Soap dies. Though, to a lesser extent.
In Vile's story mode in Mega Man X Maverick Hunter X the final boss is X and Zero fighting together. Sometimes they'll strategically swap places, but they'll also release attacks together or release them from opposite sides of the screen to trap you. When the boss health bar gets low enough, one of them will fall, but that's really not agood thing ...
You get four neatly-labelled ones, with the four-way split of your team of eight, being Zidane and Quina, Garnet and Eiko, Freya and Amarant and Steiner and Vivi. Special mention goes to Steiner and Vivi because of their in-game sword magic command combination.
Double Bash Brothers moment for the win, when Zorn and Thorn decide to mess with Eiko and Mog.
There's an implied Bash Brothers relationship between Blank and Zidane, but because Blank isn't one of your main characters, it never really appears.
One iconic moment sees Steiner and Beatrix protecting Alexandria together by bashing in the heads of many, many Mistodons.
Alex and Ryan in River City Ransom. In Japan, they're known asKunio and Riki and they continued to team up in later games (such as in Nekketsu Kakuto Densetsu and Nekketsu! Street Basket) whenever they were not competing as rivals.
In Dynasty Warriors, Gan Ning and Ling Tong evolve from mortal enemies into a grudging version of this. Perhaps most notably at the battle of Shi Ting in DW6, where if you kill one half of the pair the other will become enraged and go into hyper mode. Even before that, they were featured in the opening to Xtreme Legends.
The fight's a bit more metaphorical in Ace Attorney, but Detective Badd refers to his partner Prosecutor Faraday as his "battle-buddy" due to the many legal battles they've fought together.
Phoenix and Edgeworth fall under this too; they may usually fight against each other in court, but there are several times when Edgeworth helps Phoenix achieve the proper verdict and its obvious how well they work together, with Phoenix jumping to illogical (but correct) conclusions and Edgeworth helping him back up his claims.
Apollo and Klavier are this, starting the first time they encounter each other in court.
Donkey and Diddy Kong in Donkey Kong Country, Diddy and Dixie Kong in Diddy's Kong Quest, and Dixie and Kiddy Kong in Dixie Kong's Double Trouble.
Team Fortress 2: There's a reason why the Heavy and Medic pairing is one of the most iconic.
The Scout grew up with Seven older brothers who would roam Boston and get in fights. His speed training was for getting to the fights before they ended.
Dragon Ball Z: Budokai 2 featured this as a mechanic; on the story mode world map, letting two characters with a pre-existing relationship occupy the same space would give one or both of them a stat boost in combat, implying they were looking out for each other.
Commander Shepard and Garrus Vakarian in Mass Effect, acknowledged in-universe in the third game.
Shepard: There's no Shepard without Vakarian.
Disgaea 4: A Promise Unforgotten actually integrates this into gameplay with Valvatorez and Fenrich. Apart from starting with a very high likelihood of initiating team attacks with each other, all three of Fenrich's passive abilities are based on Valvatorez's status or positioning (ie. getting a 30% stat boost for standing next to him).
Teenage Mutant Ninja Turtles. In the 2007 TMNT movie, Splinter even said that when they work together and are in the right rhythm, they are unbeatable.
Raphael from the 2003 cartoon is very dedicated to this trope. While all the Turtles cooperate in battle, he stands out as an especially reliable back-watcher. In nearly every fight, Raph will prevent an enemy from nailing one of his brothers from behind.
Turtles Forever takes this to the apex with the '03 Turtles eventually fighting in tandem with the '87 Turtles, and the '03 style of straight ninja fighting is contrasted with the '87 slapstick style.
Transformers Animated with Prowl and Captain Fanzone when they go to Dinobot Island and have to fight off a slew of mutated creatures. It was that episode that gave some viewers a lot of respect for Fanzone, because even though he didn't like them he was still willing to work with them.
In-universe, this was probably part of why Fanzone started actually liking the Autobots, or at least tolerating them. In a later episode he even sided with them against Powell.
Another example is the big guy-little guy team of Bulkhead and Bumblebee. They've been close friends ever since attending Autobot Boot Camp together, and are usually seen watching each others' backs on and off the battlefield. The two have even developed their own variation on the Fastball Special utilizing Bulkhead's wrecking ball hands and Bumblebee's smaller stature.
Luminara and Bariss Ofee in Star Wars: Clone Wars. Their lightsaber fight against the battle droids showed them to be perfectly synchronized.
Other expanded universe material unveils that the two of them specifically learned to fight like this.
The SWAT Kats live this trope, though only rarely are they actually fighting in the same room at the same time. When they do, T-Bone acts as The Big Guy and goes at baddies with fist swinging, while the slighter Razor relies on a quicker, more acrobatic fighting style. The rest of the time, their approach to a problem will still always depend on their teamwork (whether it's air/ground, or piloting/weapons). If one kat is in serious trouble (or worse, unresponsive), the other will get very distressed and might channel that into a "this is for my buddy!" attack.
Though female, The Powerpuff Girls often fight in this manner and are closer to each other than anyone else.
Superman and Captain Marvel. Their initial efforts to take out the more experienced and ruthless Black Adam separately doesn't work well for the pair. However, once they start working together, they eventually find their rhythm and proceed to lay down a beautiful beat down on him. It was a pleasant contrast to other animated showings of the characters where the two heroes end up fighting each other.
In the US, there is an old saying, "A friend will help you move, a good friend will help you move bodies, and a brother will have the bodies moved before it occurs to him to ask why the hell you need bodies moved."
Many Ice Hockey forward lines embody a three-brother party. One of many examples would be the "Crash Line" of the New Jersey Devils teams of the 90s and early 2000s. The Crash Line was composed of Bobby Holik, Randy McKay, and Mike Peluso; the average weight of a Crash Line player was 215 pounds. Needless to say, the Crash Line was a dominating, physical and ultimately instrumental part to the Devils' championship success. They were extremely successful and provided the "grind line" defensive template that is used to this day.
Of course, the "grind line" terminology was derived from the Detroit Red Wings—who, after being destroyed by the Crash Line in the 1995 Stanley Cup Finals, quickly adopted the same techniques and established the original Grind Line of Kris Draper, Joe Kocur, and Kirk Maltby. This line led them to two straight Cups in 1997 and 1998 and permanently encoded this technique in the essence of the game.
In the late 1980s, Bob Probert and Joey Kocur of the Red Wings were sometimes refered to as "the Bruise Brothers".
When they both played for the Oakland A's, Mark McGwire and Jose Canseco were nicknamed "The Bash Brothers" for their one-two punch when put together in the line-up.
Military units in real life, particularly when performing CQB (Close Quarter Battle) maneuvers, such as rescuing hostages.
Despite the common depiction of a Cold Sniper acting alone, dedicated snipers are always deployed with a spotter, someone who can confirm the kill because the actual sniper is too preoccupied with making the shot itself. They are also one to advise on which bullet to use and what modifications to make depending on the situation, as well as double-check the distance to the target.
In fact, in many situations the spotter is the more experienced soldier, as the spotter's work is more complicated, which is saying something since doing the actual shooting isn't simple point-and-shoot to begin with.
In social situations there is a strategy involving using the Wingman, a friend that can give even the most skilled of Casanovas an added edge. Generally, they give a mutual benefit to each other by highlighting each others' strengths, as well as ensuring that neither are completely alone. While The Hero will acquire a Love Interest to become an Official Couple, because the Wingman was hanging with the hero they also look good and are often able to establish a relationship with a friend as a Beta Couple.
The United States and Australia. The Boisterous Bruisers of the English-speaking world, priding themselves primarily on how Crazy Awesome they can be rather than how "civilized" they are. The Australia-US alliance is one of the strongest in the world—possibly stronger than even the US-Canada and US-Britain ones. Since World War I, the US and Australia have always fought beside each other (even if the US was late to the party the first two times, one implies the other). See Vitriolic Best Buds for details.
...But that still doesn't mean you should shake a stick at the US-UK Special Relationship. After the twostopped fighting, they instantly agreed to bury the hatchet and become pals, and now either side can be guaranteed to back the other up. Some conflicts aside, the two will always be found together, pulling the other's butt out of the oven once shit hits the fan. There's always some guaranteed Ho Yay between the two leaders of the respective countries.