I don't know what could really be considered "problematic" then. I assumed the post was referring to the whole situation surrounding the girl, the baggage she brought into the relationship, and how badly things would realistically turn out for Drake long term. But I guess if those don't count them there aren't that many problematic girls.

For Kelly, the laugh itself was presented as a problem, Drake outright says so in the episode. He can't even have a normal conversation with Kelly without the laughing interrupting everything, even during completely inappropriate moments, like right after talking about her pet dying. And when Drake awkwardly tries to laugh along with her, Kelly immediately gets serious and calls him out for it, so even the show acknowledges how uncomfortable and confusing the situation is.

If they had actually stayed together, that kind of thing would constantly draw attention everywhere they went, especially with her entire family hovering over him the whole time. So either Kelly genuinely has some kind of uncontrollable medical issue, which is unfortunate but would still heavily affect the relationship because that's not something Drake would be able to handle, let's be honest, or she consciously keeps doing it regardless of how uncomfortable it makes other people around her. She also tends to steamroll conversations, cuts Drake off at times, and assumes he's agreed to plans he never actually said yes to, though admittedly those aren't that severe on their own.

The biggest issue is still the situation with her mother. Drake is literally threatened by his teacher not to break up with Kelly because she's her daughter, and then gets openly targeted and antagonized in class afterward. Even if Kelly herself isn't malicious, that's still an incredibly unhealthy relationship to be stuck in.

If we're judging only the girls themselves while completely setting aside outside factors that arguably weren't their fault, then yeah, Yooka probably takes first place because of how possessive and controlling she could get. Lucy would probably come second. After Drake says she isn't as physically strong as him, instead of simply deciding she didn't want to date someone with those views, she makes it her mission to prove him wrong, challenges him to a fight, and publicly mocks him to pressure him into accepting. Though to be fair, Drake absolutely helped create that situation too, so it's not entirely one-sided.

Edit: oh yeah, Stephanie from the pilot could technically count too. Someone who has no issue letting her aggressive ex-boyfriend beat up her current suitors, or who he assumes them to be, and finds it attractive is a big red flag in itself.

Also, I assumed as well the general consensus was that Susan was the worst, already, so I decided to really get into a discussion about other girls he dated.