“Cobra Kai” was such a pleasant surprise as to invite skepticism whether this long-delayed “The Karate Kid” sequel could do it again. But Season 2 of the YouTube series is, if anything, better than the first — a teen soap, largely, which also packs a wryly nostalgic kick.

Part of that has to do with the arrival of original bad guy Martin Kove, who popped up in the first-season finale and slides back into the role of Kreese as if no time has passed at all.