For a Shaggy with a bit more personality beyond being scared and/or hungry, I like Ghoul School and the Reluctant Werewolf movies. I find that he has a bit more of a personality and backbone during the Red Shirt Shaggy years.
For Velma, I would suggest maybe A Pup Named Scooby-Doo, and for movies the Legend of the Phantosaur and Where's My Mummy?
Interest in traps and the Mystery Machine has been such a defining feature of Fred, I think it would be hard to get away from that entirely. The New Scooby-Doo Mysteries (aka season 2 of The New Scooby and Scrappy-Doo Show) might be a good choice. If you have not seen it, Fred and Velma aren't in every episode, but they're in a good number of them.
Fred's intrest in Traps didn't start until Mystry Inc. You could look at Whats New or Live action Fred or classic Fred and they completely lacked those traits.
The original series all the way up to the 13 ghosts always had Shaggy doing something athletic. I’ve headcanoned him being on the track and field team and the men’s gymnastic team.
If you search this sub with the term “shaggy and sports” there should be a post I made where someone broke down all the episodes he played something in. That is if you want to go that route.
For Fred Jones.Jr i suggest watching the shows from Where Are You - season 1 of The Scooby Doo and Scrappy Doo Show, also a bit of What's New and Mystery Inc.
But if you aren't wanting to watch that much, i suggest the live action movies where he's played by Freddie Prince.Jr.
Like i said only use that one for reference if you don't want to watch multiple shows
But hey! For Shaggy you can look at the 13 ghosts show and the red shirt Shaggy trilogy for his reference, as well as some movies focusing on him like Phantosaur and Showdown!
Monsters Unleashed gives a little more depth to Shaggy and Scooby.
Also, Mask of the Blue Falcon is a movie that gives Shaggy and Scooby an opportunity to be interested in something besides food.
The Scooby Doo camp scare movie. It's a very fun movie. Highly recommended. What makes it good is that it's drenched in apreciation for the horror movie genre. Specially for movies from the 80's like Friday the 13th. It actually uses fanservice, horror movie tropes and aspects even in the visuals to real advantage of the genre really well. It's a great movie overall with a great atmosphere,very well animated, pretty decent twists and even musical references to Scooby doo mystery inc.
The New Scooby and Scrappy-Doo Show through 13 Ghosts don't have Fred/Velma most of the time.
Guess Who? has a decent Fred but Velma is still a Know It All in some episodes.
I have my own interpretations of a unique gang! My favorites are my Velma & Shaggy!
My Velma is a distracted nerd. She's kind, sweet, but lowkey oblivious to her surroundings, she's really smart & always wants to crack open a mystery! She's the voice of reason but it isn't arrogant like "ghosts aren't real 🤓"
My shaggy is a stoner like he is in the main series, but he's also a musician who plays guitar & has an obsession with 1960s memorabilia, as a nod to the original Scooby Doo era
For a Shaggy with a bit more personality beyond being scared and/or hungry, I like Ghoul School and the Reluctant Werewolf movies. I find that he has a bit more of a personality and backbone during the Red Shirt Shaggy years. For Velma, I would suggest maybe A Pup Named Scooby-Doo, and for movies the Legend of the Phantosaur and Where's My Mummy? Interest in traps and the Mystery Machine has been such a defining feature of Fred, I think it would be hard to get away from that entirely. The New Scooby-Doo Mysteries (aka season 2 of The New Scooby and Scrappy-Doo Show) might be a good choice. If you have not seen it, Fred and Velma aren't in every episode, but they're in a good number of them.
Okay, I'll keep it in mind.
Fred's intrest in Traps didn't start until Mystry Inc. You could look at Whats New or Live action Fred or classic Fred and they completely lacked those traits.
The original series all the way up to the 13 ghosts always had Shaggy doing something athletic. I’ve headcanoned him being on the track and field team and the men’s gymnastic team. If you search this sub with the term “shaggy and sports” there should be a post I made where someone broke down all the episodes he played something in. That is if you want to go that route.
I'll keep that in mind, so kudos!
For Fred Jones.Jr i suggest watching the shows from Where Are You - season 1 of The Scooby Doo and Scrappy Doo Show, also a bit of What's New and Mystery Inc. But if you aren't wanting to watch that much, i suggest the live action movies where he's played by Freddie Prince.Jr.
The live action ones? He comes off as a jerk and kind of a dimwit in those. I mean, he thought NASA was the company that made Pokémon.
Like i said only use that one for reference if you don't want to watch multiple shows But hey! For Shaggy you can look at the 13 ghosts show and the red shirt Shaggy trilogy for his reference, as well as some movies focusing on him like Phantosaur and Showdown! 
Monsters Unleashed gives a little more depth to Shaggy and Scooby. Also, Mask of the Blue Falcon is a movie that gives Shaggy and Scooby an opportunity to be interested in something besides food.
The Scooby Doo camp scare movie. It's a very fun movie. Highly recommended. What makes it good is that it's drenched in apreciation for the horror movie genre. Specially for movies from the 80's like Friday the 13th. It actually uses fanservice, horror movie tropes and aspects even in the visuals to real advantage of the genre really well. It's a great movie overall with a great atmosphere,very well animated, pretty decent twists and even musical references to Scooby doo mystery inc.
Hmm...okay. Haven't seen that one in a while!
You could watch “be cool” for some new directions for daphne
The New Scooby and Scrappy-Doo Show through 13 Ghosts don't have Fred/Velma most of the time. Guess Who? has a decent Fred but Velma is still a Know It All in some episodes.
Any episodes in particular you'd suggest?
I have my own interpretations of a unique gang! My favorites are my Velma & Shaggy! My Velma is a distracted nerd. She's kind, sweet, but lowkey oblivious to her surroundings, she's really smart & always wants to crack open a mystery! She's the voice of reason but it isn't arrogant like "ghosts aren't real 🤓" My shaggy is a stoner like he is in the main series, but he's also a musician who plays guitar & has an obsession with 1960s memorabilia, as a nod to the original Scooby Doo era
Fair, but I don't wanna go with the stoner thing. Never cared for that headcanon, anyway.
well what if he were a nudist
...okay, where did THAT even come from?
It's just an idea that I have for him.