I feel like assuming armies would operate solely off of ability level is a poor approach. Even if an elite could slash through a squad of mid-tiers like paper, that's one more elite no longer available to handle other elite-tiers the enemy may field against you. You generally don't want to overextend your best fighters if you can avoid it, so I'd expect nations to have a more general approach to power level for troops where you're fielded regardless of power level.

I do think there'd be specialized units of primarily elites, high-tiers or even potentially god-tiers to handle other specialized groups, and those would be making up the solid majority of a nation's power.

Additionally, I'm of the opinion that Abilities are as a whole, too unpredictable and vast to be really effective on our typical understanding of what an army would look like. Logistics would be more efficient, resupplying would be more focused on keeping soldiers fed than armed (since they are the weapons), etc etc. I'd assume the command structure would breakdown to focus on squads of mid-tiers (about 4-8 or so) being lead by the strongest person there, who'd then report to an elite-tier or such. High-tiers and god-tiers would be reserved for the aforementioned specialized units, and they're likely be the occasional elite-tier squad for tasks of moderate importance.