Said movie also features a spectacular Take That, Scrappy! in the form of Scooby punching Scrappy (who was, mind you, the Big Bad, and practically asking for it after trying to kill his uncle).
Special mention also goes to Shaggy during the climax, twice. First, when Scooby is about to be absorbed, Shaggy says, "Nobody absorbs my pal!" and then grabs onto the pincer to save Scooby. And again right before Shaggy pulls the Daemon Ritus out of Scrappy's chest:
When Fred falls into the path of one of the swinging blades at the haunted castle, Velma, showing amazing quick-thinking, tosses him a leather-bound book for him to shield himself with, saving his life.
Shaggy being the whole reason Mondavarius's plot gets foiled at all - by freeing his friends and stealing the Daemon Ritus.
N'Goo's attempt to intimidate Velma with a vision of a monster in the fire is foiled when she easily spots the holographic projectors behind the trick.
The random guy Velma met at the bar trying to help her after the monster knocks her out. It only gets him captured as well but points to him for trying.
Matthew Lillard's spot-on portrayal of Shaggy in the 2002 film, which eventually got him cast as Shaggy's official voice actor, a role he's held since 2010.
The original series in 1969 was the debut of legendary voice actor Frank Welker, who was 23 at the time. Over 50 years later, not only has he become one of the most prolific and beloved voice actors of all time, he's still the voice of Fred to this very day. Only very rarely has anyone else ever played the character, even in parodies. The man is still playing a teenager in his 70s, not to mention having pulled double duty in the franchise's main cast since taking over the role of Scooby himself in 2002.
Any time Shaggy and Scooby pull a fast one on the villain in their classic way, putting on a disguise and an act to fool them. Yes, it's hilarious and unrealistic, but face it: they stop being scared long enough to frequently come in close contact with the ghost, while improvising some sort of act that actually fools the ghost. Sometimes they don't even grab a disguise and they still fool them (or at least confuse them long enough for it to work).
Heck, any show where Shaggy or Daphne is in charge. They leave it to Fred and Velma when the two are around, but they are no slouches themselves, and never have been.
In 1991, Amiga made a video game...about Scrappygoing on a quest to save Shaggy and Scooby from kidnappers! The rest of the gang is mentioned, but Scrappy volunteered to go and retrieve them, showing just how far the pup has grown to be relied upon.
And his super strength is a mechanic with which you can punch the ENEMIES WITH!
What makes this so cool is that Scrappy is totally in his element and is (if the player can properly beat the game).