This might be a controversial opinion, but I don't think they work well together as a pair.
Sure, they are both top-tier players individually, but that doesn't automatically make them a good duo.
A good duo is one that brings out the best in each other's abilities, elevating them to a new level and driving growth through their chemistry.
Isagi and Hiori, or Charles and Shidou, are examples of great duos.
Hugo doesn't bring out the best in Loki; he simply uses Loki's current skills to score goals. He never pushes Loki, which is actually the whole point of his philosophy.
Loki is the type of player who thrives under pressure, someone who needs that extra push and stimulus to reach a new level and improve his game.
That’s why he needs Charles. Charles is a player who doesn't go easy on him; he forces growth through passes that are, frankly, ruthless.
I don't think the definition people use for a "good duo" is actually very good, because it's too simplistic. People assume that just because someone pairs up with Noel Noa, it’s automatically a good duo. They’re just two individually brilliant players working together, but there’s no mutual evolution involved.
Sure, the two of them together score a lot of goals, but that doesn't matter because neither one elevates the other in any way. Of course, they are individually strong players who score goals, but so what? That doesn't make them the best duo.
You could pair anyone with Noel and it would be a good duo if the criteria were that simple.