This is probably the most debated subject on RTW forums... The Legion was superior in certain aspects, which was proven at the Battles of Pydna, Cynoscephalae and Magnesia. However Pyrhhus managed to defeat the Romans, and left Italy undefeated in a battle while he used the Phalanx.
Also, it is debated that the phalanx of late was inefective since the Diadochi didn't use as strong a Cavalry that Alexander did, which is a huge part of the Hammer and Anvil tactic.

Also the phalanx could be used effectivly only on a flat terrain, while the legions could adapt to any form of enviroment