So far, Rick and Morty hasn't crossed over to the Harry Potter universe yet. Since the show hasn't made a conscious effort to do a crossover to that fictional universe, this list is beating them to the punch.
How? By classifying the personalities and behaviors of Rick and Morty characters through the most Harry Potter-way possible-- using the Sorting Hat! If these characters ever get portalled (voluntarily or otherwise) into Hogwarts, here's where each of them will go.
RICK SANCHEZ - RAVENCLAW
Right off the bat, it's a tough one. Rick Sanchez is a hefty mix of Gryffindor, Slytherin, and Ravenclase but in Hogwarts, one can only belong to one house. Among those qualities, the Ravenclaw side stands out as superior because Rick mostly runs off his superior intellect.
This has led him to invent reality-defying gadgets and devices where he literally has become a god without wanting to. He could be a Slytherin but his nihilistic tendencies and a lack of long-term ambition prevent him from being that evil.
MORTY SMITH - HUFFLEPUFF
Morty Smith starts off as a Hufflepuff and to this day (Season 4, to be precise), likely remains a Hufflepuff. Hufflepuffs are usually characters who are reserved, humble, and loyal to a certain group or advocacy.
Despite all the traumatic experiences he has undergone, Morty is fundamentally Morty-- a Hufflepuff. He still remains loyal to his family and also practices genuine concern for many living beings around him, even if a space fart proved him wrong at one point.
SUMMER SMITH - GRYFFINDOR
Summer often gets the short end of the stick when it comes to multidimensional adventures with his grandfather but with how virtuous and bold she is, she deserves to be in Gryffindor. Because despite reality not matching her expectations most of the time, Summer remains headstrong and daring.
She has certainly displayed this whether in defying the primally backward mentality of the Gazorpazorpian males or getting into a relationship with a post-apocalypse gang leader.
BETH SMITH - RAVENCLAW
Like father, like daughter, eh? Rick's air of superiority and smarts certainly brushed off on her daughter. Beth is a brilliant surgeon though she does prefer humans instead of horses when it comes to surgery, despite being a horse specialist.
Ravenclaws usually possess above-average intelligence or better compared to most. It's easy to see how much of an intelligence gap there is when Beth interacts with Jerry, oftentimes, she even sounds like her father.
JERRY SMITH - SLYTHERIN
Jerry Smith is a regular human being who likes regular human music. Jerry certainly doesn't practice much loyalty to his family and at one point, even voiced out his regret at "accidentally" becoming a father.
Most of everything that Jerry does is also to fuel his own self-esteem and insecurity. For that, Jerry would likely go to Slytherin given his tendency for self-preservation and a closeted desire to be a dominant human being.
MR. POOPYB*TTHOLE - HUFFLEPUFF
Mr. Poopybutthole has been a famously recurring character ever since the second season of the show and apparently he was a long-time family friend.
This easily puts him in the Hufflepuff house due to his unwavering loyalty to the Smiths and even to Rick himself after being invited in a heist episode. Turns out Mr. Poopybutthole's martial arts skill and academic knowledge are quite vast but chooses to stay humble with it.
JESSICA - GRYFFINDOR
Now on to other side characters because there are no more Smiths. Jessica has always been a thorn on Morty's side or has occupied a chamber in his heart ever since the show began. This puppy crush only got dispelled in Season 4, apparently.
Regardless, Jessica seems to show an affinity for popular boys and appears to be a normal daring teenager. She's most likely a Gryffindor, proudly strutting around in the school corridors enjoying her teenage admirers, Morty included.
BIRDPERSON - HUFFLEPUFF
As dry as Birdperson's personality might be, he's a friend someone can always rely on and is someone who will stick to the very end. He has been loyal to Rick ever since they met it seems and has always sided with him despite the latter's alcoholism and destructive depression.
Birdperson is also a patient and kind soul as far as bird-people go and his friendship with Rick extends to the latter's grandchildren, which puts Morty and Summer in a lucky position to have a cool godfather figure.
MR. GOLDENFOLD - SLYTHERIN
Mr. Goldenfold is Morty's math teacher and he's pretty much one of the closest characters in the show to Jerry Smith. Both of them have this repressed desire for power and status-- two things they can't obtain the way they are.
Sometimes, Mr. Goldenfold's narcissistic tendencies and closet ambitions even manifest in his dreams or he was even able to fulfill with the help of a devil. For his behavior and personality, he's getting dumped to the Slytherin house along with Jerry, they can have each other there.
EVIL MORTY - SLYTHERIN
Last but not least, Evil Morty. If there ever was a more deserving poster boy for Slytherin than Lord Voldemort, that would be Evil Morty. He has the cunning to outwit any Rick and the ambition to topple a Citadel ruled by Ricks.
Evil Morty has all the classic Slytherin traits both positive and negative and has even shown his prowess for leadership. Much like the resident Dark Lord in Harry Potter, Evil Morty is also the current big bad guy in his own show.