Honestly, the 13 Ghosts is one of the better Scooby Doo shows, and is a high 7. I really love the establishment of an overarching story arc, which allows characters to actually develop and for a grander sense of uncertainty and large scale to unfold. It also set the precedent for Mystery Incorporated to do it, which is just an unbelievably great show. I quite liked the script, with lots of clever wordplay and amusing, absurd segments (especially the episode 2 dragon interview comes to mind, but also things like Bogel and Weerd's miscommunications or Flim-Flam's ability to put on any costume and get demons to go along with it). It was also very different in its clear self-awareness and frequent pop culture references, which I think were an interesting twist and worked given the more modern and comedic vibe of the show. Some of the premises were really good, and in particular: It's a Wonderful Scoob with Time Slime and Scooby retiring and seeing the world fall apart; the circus episode 12 with the music brainwashing people; the finale with a genuine mystery of who stole the demon chest and what people's motives were, coupled by the only actual twist in the show; and to some extent the Nicara episode with her seducing warlocks and draining their power, and the ship episode with Scooby being afraid of monsters, were great and satisfying episodes. Unfortunately, too many of the episodes were never really thought-provoking or exciting because the end result is never really in doubt and there's no mystery to solve, which is the traditional crux of each episode. The monster premises, characters and humor could carry some episodes, but didn't sustainably make the show exciting. Not having Fred and Velma did hurt, as Flim-Flam was occasionally funny due to absurdity and some societal commentary, and Van Ghoul was actually an enjoyable character to have, but Scrappy didn't add anything. I do think this show maybe did the most with Scooby himself of those I've seen, as we really see him wrestle with the trauma of catching monsters and being scared all the time. I hope the Curse of the 13th Ghost movie doesn't drop the ball (as it seems many online believe it did), because this is a solid and fun show.