Placeholder until I get around to Codifying Anything Goes Skills. Feel free to suggest or design charms. Anything I like will get added here as official and credit (of course) given.
I suggest not nailing down the individual charms. It's a whole lot of work for questionable benefits. You're not running a game, so you don't have to precisely nail down people's capabilities ahead of time, and with vaguely-defined charms, you can have Ranma do crazy stuff with no justification beyond "yeah, that's something Ranma could do".
Also, keep in mind that 3e Martial Arts don't map very well to Ranmaverse martial arts techniques. Ranma characters pick up individual techniques all the time, but 3e martial arts don't let you do that - you have to train up dots in every style you want charms from, then get all the relevant prerequisite charms, so you can't just skip straight to learning the Shi Shi Hokodan without also becoming well-versed in whatever style it's a part of. (If it's even part of a style; there's not much indication of that in canon.)
That said:
Actually, Ranma probably hasn't learned the entire style. He knows the Saotome school, but not the Tendo school. Mechanically, Anything Goes probably has an oversized charmtree that branches just before the Form charms. This is good news for you! It means you have room for him to pick up lots of new techniques without having to learn an entirely new style.
Moko Kaimon Ha
Cost: 3m Min: Martial Arts 3 Essence ?
Type: Simple
Keyword: Decisive Only
Duration: Instant
Prerequisite Charms: None
A dual strike akin to forcing open a door and crashing through. The user spreads his arms apart in an opening motion while simultaneously kicking with one foot.
You can't have an entire style with nothing but decisive charms, and withering charms generally come first. Also, you definitely can't have one-to-one correspondence between named techniques and charms - there aren't nearly enough of the former.
Kijin Raishu Dan (In Progress)
Cost: 2m per blade Min: Martial Arts 5 Essence ?
Type: Simple
Keyword: Decisive Only
Duration: Instant
Prerequisite Charms: Yamasen-Ken Form, Moko Kaimon Ha
Simulating the action of flinging shutters open, the user's movement are so swift that the air itself is forced apart, creating a vacuum of sharp blades of air capable of cutting through even metal.
The Martial Artist makes a Decisive attack on all targets, friend and enemy, in a line out to medium distance. Add 1 dice to your chance to hit for each blade. Add 2 dice to your raw damage for the first blade and 1 dice for each additional blade. The user may create up to Essence x 5 blades per attack. Any object in the path of this ability recieves an additional 12 dice of raw damage. Due to the nature of the blades these attacks cannot be parried except by charms or techniques that explicitly allow the parrying of such attacks. (eg. Heavenly Guardian Defense).
Mastery: At Martial Arts 5, Essence 4 this charm can be rebought to reduce the cost to 1m per blade and essence x 7 blades per attack.
Good god. 10 motes for a full-damage multi-target unblockable medium-range decisive attack with five extra dice to hit and +10 damage? No-ho-ho-ho-ho.
Hell no! You don't even get that kind of nonsense from a doom combo, let alone a single charm.
Unless, of course, each blade is a separate attack. In that case, it's
even worse, because you can throw an insane number of attacks insanely cheaply and trivially mash your opponent's defense down with onslaught penalties. It would be a "Bulwark Stance or die", except Bulwark Stance doesn't even work because it's unblockable. (And even if it did work you're rolling so damn many attacks a couple of them are probably getting through anyway.)
Kijin-Gun Dai Ranbu
Cost: 15m Min: Martial Arts 5 Essence ?
Type: Simple
Keyword: Decisive Only
Duration: Instant
Prerequisite Charms: Kijin Raichu Dan
The second ultimate technique. Similar to the Demon-God Multiple Strike, with the user spinning to fire off multiple bladees of air at random.
All targets at up to medium range are subject to a Decisive attack of (essence x 2) blades of the Kijin Raishu Dan, both friends and enemies are subject to this attack.
Mastery: Reduce the cost of this charm to 10m and make (essence) blades per target undodgeable.
Even more stupendously overpowered. Unblockable undodgeable attacks are goddamn nitroglycerin - if you're not very, very careful with them, they will blow your game right the hell up. There are only three unblockable undodgeable attacks in the corebook. One is a withering attack that only works on enemies who are already crashed. One is a withering attack with extremely specific requirements. The only decisive among them is Blinding Nova Flare, which requires you to land a difficulty 5 gambit first, so you need to have both your normal initiative pool and your second initiative poll from SPSITV Form at "if I hit you you're fucked" levels, so it usually only works on guys you're already wrecking.
I'd like to reiterate here, that I strongly recommend you not write full-fledged charmtrees for these styles. You don't need to be a good homebrewer to write a good fanfic.
I've gone and changed the post. I've moved it to apocrypha where it belongs, and made a few changes. (on a side note nothing says you can't have a charm tree full of nothing but decisive attacks, its probably very stupid though 
). In all honesty Ranma 1/2 martial arts probably map better with the 2e system where withering/decisive isn't a thing. Lets... lets just consider this a colourful (and probably very bad) essay into the art of homebrew and leave it at that. I'll leave the post as an archive if people want to speculate about what charms might be like. 
