"Signature Technique" revealed so far: (Warlords, Admirals, Yonko, Revo Leaders ... etc)
(It should be Noted that it's important to know Signature Techniques cuz Ultimate Techniques will be based on them)
* means those Ultimate Techniques could get Upgraded & are not Necessarily The Best we will see of them till Manga Ends
(Luffy & Jinbe are Excluded)
Buggy ---> Bara Bara Ho (Bara Bara Festival*)
Crocodile ---> Desert Spada (Desert La Spada*)
Blackbeard ---> Black Hole (???)
Moria ---> Doppelman (Shadow Asgard)
Kuma ---> Pad Ho (Ursus Shock*)
Hancock ---> Mero Mero Mellow (Slave Arrow*)
Law ---> Room (K-Room*)
Doflamingo ---> Parasite (Birdcage)
Aokiji ---> Ice Age (???)
Kizaru ---> Yata No Kagami (???)
Akainu ---> Dai Funka (???)
Fujitora ---> Gravito (???)
Ryokugyu ---> Kinniku Mori Mori (???)
Garp ---> Galaxy Impact (???)
Big Mom ---> Soul Pocus (???)
Kaidou ---> Bolo Breath (Kaen Daiko)
Shanks ---> Divine Departure (???)
Sabo ---> Ryu No Kagizume (???)
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@ConquistadoR
This means that Major Characters remaining without their Signature Attacks Named are:
Mihawk - Dragon - Whitebeard - Sengoku - Weevil
Weevil is a Post-TS Character & We barely saw him, that's why we haven't seen his Attack yet
Whitebeard was seen Fight to The Death (But it seems Oda will Hype his Signature Attack in a New Flashback similar to Oden or Roger)
This means:
Out of Marines (Admirals), Oda chose to keep Sengoku The Buddha Last
Out of Pirates (Yonko/Warlords), He chose to keep Mihawk The WSS Last
Out of Rebels (Revos Army), He chose to keep Dragon The Worst Criminal Last
While Garp, Shanks & Sabo are simply Runner-Ups (2nd Strongest) but have Greater Influence
And Story started with Luffy, Zoro & Koby (Do The Math) ---> Oda literally used a Narrator Box to Separate between their Arc & Rest of Story