Looking for advices with the use of elite hoplite units.

[Titus Marcellus Scato]

You mention that you always play on M/M. I was wondering how to find a balance between the weakness of the AI factions in medium setting and the repetitive waves of full mercs stacks that makes the hard setting a bit tiring. Do you use house rules to re-balance ?

Yes, I do use house rules.

1. Always prioritise town building over army recruitment, except when faced with an invading enemy.
2. Annex new territory only for a good reason, e.g. if economy not making enough profit, or to replicate historical achievements, or to control Homeland provinces. Otherwise stay at peace whenever possible if civilised, or if barbarian, just raid and loot enemy provinces and then withdraw.
3. If earning too much money, spend it on expensive things like mercenaries and ships. Or give large donations to your allies.
4. Never, ever completely destroy a AI faction until you want to achieve your victory conditions at the end of the campaign (e.g. I defeat Rome by taking all Roman provinces apart from Rome itself, which I leave alone until the very end.) Otherwise, leave the enemy faction with at least one city.
5. Never destroy wonders for easy money, only destroy for a good reason (e.g. they were built by an especially hated enemy.)
6. Use as many mercenaries for offensive operations as possible. Recruit as few troops as possible from towns and large towns, unless needed to repel a foreign invasion - recruit mainly from cities.