Just straight off the bat:

• Detective Pikachu has the experience with the supernatural to determine the nature of the Death Note and while channeling the detective expertise of Harry Goodman would eventually root out the identity of Kira.

• The Scooby Gang would never figure out how the Death Note works because they always end up concluding the monster is just a guy in a mask.

• Benoit Blanc trivially dismantled the Rub-Goldberg-esque machinations of Miles Bron's Glass Onion, but was unable to save several people from dying (or nearly dying) before the climax of each movie. Also, he's way too trusting of the police. So he wouldn't deduce the identity of Kira.

• Sam & Max typically bungle their way through a case by way of hijinx, without ever solving anything, and just sort of land on a conclusion by accident, only to resolve the causal sequence in retrospect. They would not solve the case, although they would annoy the piss out of Kira and probably cause him to fumble the Death Note in a way that ended with him killing himself in the process.

• Dexter would definitely figure out who Kira is, but wouldn't bother fucking around with how the Death Note works, because he only likes killing people his way.

• L is nowhere in the top right panel