Playing Epeiros too, and having annihalated the Romans in 5 consecutive heroic victories, before wiping them out as a faction, a large part of my army consists of hastati, since they are so numerous, supporting the rarer Pezhetairoi, Chaonion Agema, and Illyrioi Thorakitai arrayed behind them. 2 units of elephants anchor each flank, destroying enemy cavalry, while the fast moving Molosson Agema and Prodromoi flanks the enemy. The hastati keeps getting completely slaughtered by the huge stacks of elite Seleukid armies, but Roma has a 6% growth rate each time I exterminate the populace, so its nothing.