(Assuming by the end of ARC-V it’s canonically revealed the Yuyas and Yuzus were all originally one male and female and they’re basically siblings.)

AU where the Yus are siblings who go to the same school and was good in a class that had NOTHING TO DO WITH DUELING:

Yuya: Acting/Drama (Face it, with his Entertainment Dueling background and all the shit he’s been going through, I’d think he’d have plenty of experience.)

Yuzu: Music and Choir (Need I even explain it? She’d probably have a solo performance in the school choir. That is, if she hasn’t already made the choir part of her ever-growing harem sphere of influence.)

Yuto/Ute: Language and Mathematics (Let’s face it, he’d probably do better with his XYZs than the other Yus can do their ABCs. He’d probably be the one who has to drag all of the others out of the eternal pyre that is Advanced Math Hell.)

Ruri: Biology and other Natural Sciences, including Health and Nursing (Truth be told we don’t know much about Ruri yet, but considering what Shun and Yuto say about her being a caring person and that she was a relief staff member of the Resistance, I can fancy an idea.

Yugo/Hugo: Team & Club Sports (He’d probably suck at most classes but would be a great asset to the Cross Country Team and the Robotics Club
not to mention the Synchronized Swimming Club.)

Rin: Home Economics and Crafts (I have the distinct feeling that growing up with Yugo, she’d be pretty good with her hands. Maybe be into baking or making pottery. Like, really nice pottery.

Yuri/Joeri: Chemistry/Chemical Engineering and Political/Social Sciences (Yuri probably has a weak spot for blowing up shit by fusing shit. And considering that he’s Academia’s apparent secret weapon an that he’s held in extremely high regard and fear, he probably knows his way around how people work. Easy A’s.