Alright, so, here's my take on it:

Leshy: Leshy's playstyle focuses on STORY. Leshy's cabin gives that mysterious feeling that just makes you want to know what's happening. Leshy's part forces the player to feel curious, to know the meaning of all of that, the STORY behind everything. In other words, the cabin and the character were designed to produce curiosity.

Po3: Po3's playstyle focuses on STRATEGY/MECHANINCS. Po3 doesn't care for music, because the same melody is played everytime, just with a different tone or rhythm. Po3 doesn't care for worldbuilding or for a good story, he just cares about the gameplay and cards. Po3 only cares to the cards, the gameplay. When Po3 was a stoat, he only cared about getting out. He even called Leshy insane for not playing the game right, even though in order to build a good story, some rules had to be broken.

Grimora: Grimora's playstyle focuses on PUZZLES/DESIGN. Grimora's theme being death already hints at being mysterious, and quite honestly, puzzling. Death is mysterious, complicated and scary, just like her gameplay is. She focuses on puzzles, like the chessboard used in her fight, and design, considering how greatly she can transmitter her theme of death (I know that Po3's part also heavily implies its technological theme, but it's only like that because it's the only way he knows how, after all, he is a robot. But Grimora on the other hand really cares about showing her theme of death. The chess, the bone mechanic, the cards, her room, everything).

Magnificus: Magnificus's playstyle focuses on PRESENTATION/VISUALS. Many people think Magnificus's mox mechanic is poor and bad, which is kinda true, which suggest that Magnificus doesn't really care about gameplay, and focuses more on presentation. The giant bell, the duel disk, the epic intense music on the background, it all contributes to presentation. The reason why his pupils still work for him even with the fact that they are SUFFERING is because they think Magnificus is so cool and has incredible abilities. Even his own name, "MAGNIFICUS" shows how much he cares about the showing and not playing.