Cobra Kai co-creator Hayden Schlossberg says that Mr. Miyagi is the most powerful character from The Karate Kid franchise. Mr. Miyagi (played by Pat Morita) was the sensei of Daniel LaRusso (Ralph Macchio) in 1984's The Karate Kid, who trained him to defeat his nemesis, Johnny Lawrence (William Zabka) of Cobra Kai, at the All-Valley Karate Tournament. Mr. Miyagi was trained in traditional Okinawan Karate by his father. Decades later, Mr. Miyagi, a WWII Veteran working as a handyman at an apartment complex in California, saves Daniel from a brutal attack by Lawrence and his Cobra Kai teammates, setting off the chain of events that continue to reverberate into Netflix's Cobra Kai series.
Cobra Kai was founded by John Kreese (Martin Kove), a Vietnam Veteran who learned martial arts from Master Kim Sun-Yung in South Korea. Kreese would later train his friend Terry Silver in Vietnam before they both returned to South Korea to continue training with Master Kim Sun-Yung. While he's never seen, Sun-Yung is mentioned multiple times in The Karate Kid: Part III when Silver first appears in the franchise and has yet to be portrayed in live-action.
During a Twitter Q&A session, Schlossberg was asked who the Top 5 characters in The Karate Kid/Cobra Kai series are in order of "Brains and Brawn," to which Schlossberg gave a breakdown. The creator cited Miyagi as the strongest under "Brawn." The second in that list was Master Sun-Yung, making both the founders of Miyagi-Do karate and Cobra Kai karate the top contenders, which makes perfect sense given the rivalry and competitive strengths of both styles. Check out Schlossberg's response below, which also outlines the "Brains" of the question with some interesting answers:
While the "brawny" Mr. Miyagi served as Daniel's first teacher, he wasn't the only one to take up the mantle. Thomas Ian Griffith returns to the role of Terry Silver in Cobra Kai season 4, which debuts on New Years Eve. Silver was a manipulative and violent "instructor" to LaRusso in The Karate Kid: Part III, and judging by the trailers for Cobra Kai season 4, it looks like not much has changed. Griffith hasn't acted since 2007, so his return to Cobra Kai will be not only a big moment for the show, but for the actor himself as well.
Mr. Miyagi has always been the backbone of The Karate Kid series, showing his wisdom, skill, and patience above all other adversaries. While he had some tremendous struggles throughout his life, Miyagi rose above those challenges to become a wise old sage that always knew the right answer when confronted with a difficult task. While Mr. Miyagi didn't look imposing in the slightest, his speed, grace, and skill made him formidable enough to consistently take out groups of attackers with ease, be it from Cobra Kai or otherwise.
Source: Hayden Schlossberg