For Macedon,
Pezhetairoi - +3 combat strength vs. spearman, additional +6 combat strength vs cavalry, and +6 combat strength vs. melee units, Enemies have +50% flanking bonus. Pezhetairoi were the backbone of the Macedonian army, and their Sarissa spears would be able to impale enemies before they came into reach. Philip first used them, and successfully defeated his enemy in the Battle of Chaeronea. Unfortunately, Sarissa spears lacked maneuverability, therefor a flank could be more effective.
For Persia -
Persian War Elephant (To counter India's Varu) - Replaces horseman, uses heavy cavalry tree, is not effected by enemy combat bonuses. Although the War Elephants the Persian's used in the Battle of Gaugamela were of Indian Origin, i think it would be cool to have another war elephant unique unit that could match up against india's Varu.
Sparabara - Unique melee unit available with the Bronze Working tech, +5 combat strength when defending adjacent to a friendly archer, enemy archers cannot shoot past Sparabara (They must shoot the Sparabara.) Does not upgrade into an Immortal. (60 production cost, 28 combat strength)
EDIT: Also one more thing, do you know if you could change the U-boat? Since the U-boat in real life wasn't really a ship that did well in the ocean, and was more of a trade plundering vessel I have an alternative.
U-boat - +100% gold from pillaging, +1 sight, +1 speed, can pillage traders from 1 tile away and costs 1 movement to pillage.
