Scooby Doo
Characters
Norville "Shaggy" Roberts - All jokes about his supposed status as a pothead/flower child notwithstanding, Shaggy is clearly a very low-level druid. Though he is not seen creating infusions, it is clear that Scooby Snacks are Constitution and Will-enhancing alchemical items of that nature, and he'd need to be a druid to activate them. He had an animal companion (Scooby, who is now awakened and a standard companion instead) and virtually no combat ability whatsoever. Shaggy may, in fact, be a half-elf, as he clearly has not received the bonus feat at first level that a human would get. We'll call Shaggy an Expert 1/2 (emphasizing driving and mechanical skills)/Druid 1/2 (using the optional "multiclassed first level characters" rule from the DMG). His only decent stats are Constitution (he makes a lot of Fort saves against being knocked unconscious by pratfalls) and Strength (ever try holding a cowering Great Dane in your arms?) Shaggy's Will rolls are always pathetic and his Dexterity is abysmal. Feats include Run.
Scooby - Scooby was probably originally Shaggy's dog animal companion, having gone through some sort of awakening. Other than being a talking dog, Scooby can't do much. Of course, he has the scent special ability. Let's say Scooby is a Commoner 1. His stats are probably similar to Shaggy's, though he is not as strong. Feats include Run.
Daphne Blake - Daphne is probably just an NPC who tags along. The DM might have imposed her on the party as an easy "carrot" to drive the party to some conclusion, as she is kidnapped and/or separated from the group on a regular basis. commoner 1 with high Charisma and abysmal Intelligence and Wisdom. Feats include Run.
Fred Jones - Aside from Velma, Fred has the only brain in the bunch, and even he's no Einstein. We'll be generous and give him an Intelligence of 12. Expert 1, specializing in Search, Spot, etc. Seems to have a high Charisma, as Daphne digs him. Feats include Run.
Velma Dinkley - The real brains of the operation, Velma is pretty quick on the uptake, though she seems to have some sort of Anti-Alertness feat, particularly when she loses her spectacles of vision[/b]. Velma's certainly no beauty and her personality grates a bit, too, indicating a low Charisma. She's moderately intelligent and perceptive, however, probably in the 13-14 range in each. Expert 1, emphasizing Profession (Investigator). Feats include Run.
Highlights and Gaffes
Are you kidding? There's no combat and no actual spellcasting, so D&D can hardly begin to describe the action, mechanically. There are a lot of failed Sense Motive rolls and a good number of failed Jump, Climb and Swim rolls, as well as flubbed Reflex saves.
The Mystery Machine gang's adventures are so broad in scope that a single summation can hardly suffice. Nonetheless, I will try:
They go someplace that is supposedly haunted, but it's actually a minor character from earlier in the story in disguise. Scooby and Shaggy are bribed with food. Velma (or sometimes Fred) explains the mystery at the end of the show.