It's a canon fact that if a Ranma 1/2 writer wants to introduce a new technique or two without having to introduce an Original Character to teach/display it, the Amazons (i.e. Cologne) are the best option to do so. I've technically asked this before, but this time I'll come right out and say it: I'd like people to contribute their ideas on martial arts techniques that Cologne or another "Amazon Sensei" could pull out of their hat for various story-related purposes, be it a new move to teach to Ranma, something for them to use in a climatic battle, or any other reason.
To help inspire, here's a list of the Joketsuzoku techniques that I can recall from the anime (predominantly) and the manga (on occasion). The Dance of the Great Fire Dragon and Great Dance of the Super Phoenix moves have both been left out because A: they were jokes and B: they were technically items, not techniques. Mousse's Hidden Weapons techniques and Shampoo's Martial Arts Takeout techniques have also been left out. Someone in the "Cologne Vs. Happosai" topic in the Ranma section once noted that the Joketsuzoku 'style' seems to revolve around/rely on 'external ki' techniques- that is, moves based on manipulating the ki in one's environment rather than the usage of one's own personal ki. How accurate that is, I can't say.
Splitting Cat Hairs: the user seperates into a circle of 18 illusionary copies, which then begin spinning rapidly around the target, allowing the user to strike them rapidly without being struck back. Ranma defeated this move by using a piece of chicken to lure out the hungry real Cologne.
Kachu Tenshin Amaguriken: a speed-boosting training technique practiced by attempting to pluck chestnuts from a fire with one's barehands. Made out as more of a real technique in the anime, where Ranma calls the name before he 'focuses' into the super-rapid-fire-strike attack.
Bakusai Tenketsu: a technique designed more for construction work than combat, the Bakusai Tenketsu is still a legitimate threat. By repeatedly slamming headfirst into boulders, the user eventually learns how to destroy any inanimate material with a touch of a finger due to the ability to see the "breaking point" with their mind's eye. The torturous training also greatly increases the practicioner's stamina and durability, so that they become much harder to hurt and can take more damage. In the anime, a skilled user can use this move without even touching an object, as well as 'channelling' the breaking point through a medium (Cologne strikes a falling iron bar with her staff so that it disintegrates).
Fist of the Ice Bear: an elemental/telekinetic attack used in cold environments. The user levitates nearby ice boulders and hurls them mentally at an opponent. The name seems to be because the favored 'use' for this technique is to create a life-sized grizzly bear statue of ice and use it as a mount/weapon.
Air Manipulation: a similar attack to the above, the user can create powerful wind vortexes and even fly by floating inside them and directing the whirlwind in the direction you want to go. Smaller, focused, horizontal vortexes can also be used to strike at foes. In fact, the precise limits of this technique(s) is unknown; the above are merely the uses displayed in the episode.
Shark Fist: another elemental/telekinetic attack, requiring an abundant supply of water nearby, the user can direct a high-pressure blast of water at a foe.
Animal Summoning: Cologne once summoned a shark and used it as her obedient steed. Presumably, other animals could be summoned in the same way.
Xi Fa Xiang Gao: this shiatsu attack targets pressure points on the head and requires the application of certain, unidentified herbal extracts to work. It allows the user to modify the memory of the subject, erasing and possibly even replacing and/or installing memories as they see fit. This attack has been refined in such a way that the user can disguise what they're doing as a bit of haircare.
The Amazons also seem to know about ki blasts, as Cologne displayed one when she and Happosai were introduced in the manga take on the Love-Pill Bracelet story, and she gave Ranma advice and some training on the Shi Shi Hokodan in the anime's take on the story.