I like the idea of changing up the current Anbu system (perfect time for that, I suppose). But I'm not sure what motivation the clans have to spill their secrets, especially the ones that they're not comfortable giving away to the "common" Leaf nin. There's no reward and they're already uncomfortable giving away their more harmless/useless/common techniques away, so why would they give their more important/vital ones?
I doubt that the Anbu-only policy would last long, especially if it excludes the Hokage. Ninja copy and steal techniques. It's the way way of a ninja to cheat and most ninja only shrug and go "yeah, they're ninja. What'd you expect?" So even if there's an official policy of Anbu-only pool of techniques, I doubt that it'd stay that way for long. Jutsu Hackers are a thing and not all ninja have Leaf's honor-policy. And if an Anbu-only technique spreads to even one person outside of op-sec, then that blows away the "retraction" option that the clans have. I suppose it's possible, but it'd need some serious op-sec policies to ensure security, along with some serious motivation that even outstrips the rewards of Asuma's current competition --which has some pretty hefty rewards.
And for the "loyalty to only the Leaf..." well. That sounds a little too much like Root for me to be comfortable with. It seems like a slippery slope to go from "loyalty to the Leaf" to "if it's for the Leaf," to even "Anything for the Leaf!" And that's how you get Root-sponsered genocides that lead to Pain becoming a thing.
All in all? I think it's a good idea, just needs more polish. Depending on the details, I'd vote for it.
First of all, I appreciate the feedback and the encouragement, thank you. Now let's go into the polishing state thanks to the feedback
Motivation: Fair Enough, so let's see what we can use to bring the Clan to accept
1)Goketsu acceptance of the motion, leveraging our loyalty to Leaf to force the most loyal(*cough* Inuzuka*cough*) to follow us simply to not do "less" than the foreign[Asuma can use some of Jiraya's seals as our contribution to the ANBU]
2)The Danger of the situation, in which strong ANBU could save the village
3)The fact that don't really lose anything, their secret remain safe and only used by ANBUs(also used selectively, not all at once)
4)The honor of naming and being responsible for creating the future heroes of Leaf(Create one ANBU for clan?)
5)If Asuma is on board, it's already two clans(Sarutobi+Goketsu), As long as we can convince enough to make refusing shameful, things will just snowball(ISC could see the appeal of stronger ANBU and accept, making everything after than pretty easy)
6)Some prize for the clan that accepts?(Ex.The techniques give will count for the competition, but won't be shared?)
7)Maybe give some choice where to sent these new ANBU to the Clan Council? With the Hokage having two or three times the vote of the clan? That would be pretty interesting for the Clans
Stealing Techniques: This is pretty much technical, much like Clan Secret,so it something that should be worked on by the Tower/Nara, regardless we can create an idea on where to go
1) Techniques are only teachable for the given ANBU designation:
(Example. "Sword" is the only person that can learn techniques gifted for "Sword Designation ANBU", no one else), this means that only one person knows the techniques, therefore the chances for the techniques being leaked become minimal.
1.a) I would propose this because an ANBU-only pool, well, means you need one ANBU leaking techniques or making an error, to lose all the techniques and i assume this is a risk the clans wouldn't be ready to accept
2)Penalty for leaking techniques to others is extremely harsh: Shadow Clone/Leaking Clan Secrets harsh
3)Clan found out "stealing" or trying to "steal" said techniques will receive
harsh sanctions by all the other clans+Tower
4)Maybe give authorization only to proven individual(Much like SCs)
I assume Jutsu Hackers don't count, but it's an important question, what happen if a Jutsu Hacker re-invent, for example, the Nara's Shadow Jutsus, without stealing anything? Literally making it from scratch? Something to resolve, but i imagine Leaf already has a solution or the Jutsu Clan would be, well, without unique Jutsu by now.
With "Loyalty to Leaaf", i mean in the sense of the normal ANBU corps, that are loyal to the Hokage and not singular clan, meaning said clan shouldn't fear a Sarutobi ANBU stealing everything the second he/she/it get the techniques.
Also, i'm quite sure Haru would like something like this, because "more power to the clanless".