Celto-Hellenic hoplites are best used as reserve troops on the flanks of your phalanx to wrap around the enemy. The enemy will usually try to attck the units on the immediate flank of a phalanx and the celto-Hellenes have enough holding power to force them in towards the center where they get mowed down. My current Pontus campaign is at 245 BC and I own almost all of Anatolia and have forced peace with AS and Ptolies.