Characterization and interaction. Have something the reader/viewer can relate to or like in the Hero that otherwise isn't found in the others.
Likewise have your Hero have believable interactions. Meaning if The Hero
and The Lancer
are Type 2 Vitriolic Best Buds
(with a side helping of With Friends Like These...
), show it and don't make the situation such that the Hero always wins reducing the Lancer to a Commander Contrarian
always afflicted by the Conflict Ball
. Have the arguments and fights go back and forth, each side occasionally having a point or advantage when doing so. Not everything interesting going to just the Lancer or the Hero.
Additionally, flesh out each character's personality. Standardized leader syndrome usually results from placing the focus on one character (usually created first) for the Hero role and then when making the rest coming up with new and better ideas applied to the rest. When making a Five-Man Band
, if you can make all 5 their own distinct personalities, you'll have already taken a great leap to averting this problem.