What is a Champion (Suppressor) dragon good for in Dragonfire?

The Champion is the Suppressor breed: its job is to smother the enemy and to hold the Center of the formation, because that's where its aura spreads to the whole line.

Champion auras are the strongest on average: Ebbing Fury (−27.5% enemy damage), Champion's Brilliance (+15 Strength/Intelligence/Instinct), Clever Maneuver (+25% Intelligence, +15% Initiative). Its damage is mixed rather than specialised, so it fits anywhere.

In practice: put your best Champion — Seasmoke, Rhysarion, Kalspire — at the Center so its aura covers the whole line. It's the pivot of a solid formation.