The only time I "need" the poison badly is vs earth that have healers. The heal will be blocked by the ignition, remove the ignition but usually leave the poison to DoT pass the shield(most healer only remove one debuff per target per action), thus killing them eventually. Other than that, the poison is rarely enough to win or lose the battle for me.

That said, earth is hard enough to kill as is, I'm not entirely sure how I can deal with them as a wind w/o the dual debuff. Sure, he can at least still stop the heals, but now it will be harder to damage pass the shield.

No, each of them also take damage from a specific element, so you could use suigetsu for water, sasuke for lightning etc to pass them.
poison was just the "cheat" because it works against ALL of them, it's perfectly possible to pass the exam using method that is, for lack of a better word "intended", thou obviously much harder.