Dodge, duck, limbo dodge, jump, throw the trash can, drop the vase, spill the oil slick, slip and make a hit, and win without even throwing a punch. All in a day's work for Improv Fu.
A character's fighting style isn't so much as fighting as it is making up new and ridiculous ways to combat their opponent. Perhaps they don't like violence, or perhaps they never learned Kung Fu, or perhaps they just can't catch up. Either way, they find a way to be useful.
Improv Fu tends to involve quick tricks, trips, traps, a lot of dodging, and heavy implementation of objects or the environment available at any given moment. Sometimes the character essentially blunders through combat. Most of the time Improv Fu is played for comedy. May lead to Improbable Use of a Weapon if they find one they don't know how to use. A more specific case would be Within Arm's Reach (where a character is being brutally attacked and manages to just happen to grab something that they can use to fight back).
It's essentially in-universe Improv for combat, a combination of Indy Ploy and Combat Pragmatist with a lot of Improvised Weapons. This is like an Indy Ploy specifically for fighting and while this is similar to Combat Pragmatist, the Combat Pragmatist usually uses "dirty tactics" to gain the upper hand rather than fighting indirectly to ameliorate their disadvantage.
Related to I Know Mortal Kombat. Compare to Confusion Fu. Usually involves an Improbable Weapon User. See also Geo Effects, which involves incorporating the use of the field and terrain to one's advantage or disadvantage (e.g. lava lands, stages with collapsing platforms, etc.)
- Minako Aino in Codename: Sailor V has shades of this, having gone so far to weaponize mosquito-repelling incense (to be fair, the youma of the week is a mutant mosquito with an army of the standard insects).
- Fist of the North Star: Jyuza gave Raoh one hell of a Humiliation Conga with a fighting style he invented on the spot. The fight ends with him stealing Raoh's horse, Kokuoh.
- Mobile Suit Crossbone Gundam's protagonist Tobia Arronax makes extensive use of this, thanks to his being a very quick thinker. His bag of tricks includes including throwing logs (and enemy machines), using a re-entry pod to disguise his attacks, and in one memorable instance crafting a balloon shaped like a bunch of bananas to distract a group of psychic monkey pilots.
- This is Luffy's main fighting style from One Piece, as he'll use anything available to him so he can win. This causes his opponents to underestimate him because, more often than not, it looks like him fooling around rather than fighting seriously.
- Pokémon: Ash Ketchum occasionally comes up with these in battles in order to counter a particularly tricky opponent. His most famous and popular one with the fans by far is the Counter Shield technique he developed in the Diamond & Pearl series.
- Ranma ½: Ranma Saotome has this trope reconstructed, featuring an as-serious-as-it-can-get Anything Goes Martial Arts dojo. While the fighting style has some of its own unique characteristics, Ranma's most distinctive ability is being able to adapt with remarkable skill, something that comes in handy when forced to engage in all sorts of rule-restricted Martial Arts and Crafts.
- To the Stars: Magical Girls are instructed to make up new stuff in combat, since that's how they develop and expand their powers.
- Jason Bourne is a master at this.
- In The Bourne Identity, he uses a ballpen to great effect against the first killer that's sent after him and Marie.
- In The Bourne Supremacy, he beats the shit out of a fellow former Treadstone agent with a rolled up newspaper and blows up his condo with said newspaper when he's done.
- In The Bourne Ultimatum, he uses anything he can gets his hands on in a Tangier apartment, from books to towels. His foe meanwhile tries to hit him with a hookah, then grabs a razor blade.
- Jackie Chan's characters are all about this. This is because the Chan man loves action but dislikes violence so he uses his own style which involves a lot of dodging and using the environment to combat his opponents. He's beaten people up with dresses, folding chairs, Legos, their own clothing, and most infamously a 10' tall stepladder. This is also true for his character in Jackie Chan Adventures.
- Gamera vs. Guiron: At one point, Gamera swings on a huge horizontal pipe like it's a gymnast's parallel bars. No, seriously.
- This was comically sent up in the Almost Live! sketch "Mind Your Manners with Billy Quan." Billy and his antagonist would always fight using items around them as stand-ins for martial arts weapons. (In a computer room, floppy disks became shirukens; in a meat market, links of sausages became nunchaku, etc.)
- Kaizoku Sentai Gokaiger's Green Ranger, "Doc" Don Doggoier, is a Lovable Coward who resorts to tricks like hiding in brush, Explosive Barrels, and even breaking out a squeaky mallet at one point. Then there's the episode where he mans up...
- Power Rangers:
- It has many examples of Improv Fu, but the most egregious one is that a lot of fight scenes throughout the series features the Rangers fighting grunts in a playground and use the equipment to augment their fighting.
- Mighty Morphin' Power Rangers: Billy the Blue Ranger of the team kind of sucks at fighting, but he manages by using this trope, though by the time he leaves the Rangers he's gotten much better at hand-to-hand.
- Power Rangers Zeo: Occurred with Bulk and Skull when they were accidentally sent to a coliseum in another world and they get saved by another warrior, they have to face down a few guards and ultimately, they were able to take them down with the power of bumbling around.
- Power Rangers RPM: Ziggy The Plucky Comic Relief became a Power Ranger by accident and out of desperation so he had no qualifications or skills to actually be a good fighter. Instead he mostly runs around a fight scene dodging enemies or using nearby props as weapons and ways to protect himself. He gets better at hand to hand throughout the series though.
- Spider-Man: Shattered Dimensions: The Spideys mostly rely on their acrobatics and super strength instead of any set form. Well, except for Noire, who somehow knows Chinese Kung Fu.
- Ultimate Marvel vs. Capcom 3: Frank West and Phoenix Wright fight like this because they're Badass Normal Action Survivors in a World of Badass where everyone else has superpowers or fighting skills befitting soldiers and martial arts masters.
- Clementine is most definitely an ardent practitioner of this in The Walking Dead: Season Two. If someone or something is threatening her life she will survive the encounter, whether that involves running, biting, kicking, using anything that's laying around or even letting a nearby Zombie have you for lunch. She'll do anything to get out of there alive.
- Sokka of Avatar: The Last Airbender is a Badass Normal warrior in a group where all the other members have Elemental Powers, so he has to work with what he has, be it books, stink bombs, or clouds. His ability to improvise plans was part of the reason the master Piandao accepted him as his student. Creative thinking, in his masterly opinion, is the key to victory.
- Krav Maga is a martial art that teaches improvised combat techniques.
- Many self-defense courses focus on using whatever you have in your hand or around you to incapacitate the attacker or put him at disadvantage while you're running away.