Iberians, imo, are overpowered in terms of tanking. If you have ~4 garrisoned fortresses with a row of 20 champion cavalry skirmishers behind them, it is virtually impenetrable. Rams and elephants are reduced to dust by the time they reach the fortresses due to the champion cavalry skirmishers (and fortress arrows). Catapults are taken down extremely quickly by the champion cavalry skirmishers (from a safe distance). Spearmen are also not able to counter them without suffering heavy losses from the garrisoned fortresses.