The early manga doesn't, I think, really have much room for Sangnoir. Yugi or one of his friends is treated badly by a bullly (often beaten up), and the Yugi within Yugi uses a game to exact rough justice. Lather, rinse, repeat.
The one story I can see our protagonist making a big difference in is "American Hero" in volume three. Yugi's even wimpier classmate Hanasaki is a big fan of American superhero comics, especially "Zombire" (a Spawn homage.) His indulgent father gives Hanasaki a Zombire costume, which apparently gives the boy the ability to take on multiple criminals twice his size.
Having a "real" superhero there to give Hanasaki some pointers (and maybe even real powers!) could make a big difference.
The one story I can see our protagonist making a big difference in is "American Hero" in volume three. Yugi's even wimpier classmate Hanasaki is a big fan of American superhero comics, especially "Zombire" (a Spawn homage.) His indulgent father gives Hanasaki a Zombire costume, which apparently gives the boy the ability to take on multiple criminals twice his size.
Having a "real" superhero there to give Hanasaki some pointers (and maybe even real powers!) could make a big difference.