But Alexander and Phillip showed that the phalanx could be used on just about any terrain. I just think the successors misused them really badly.
Hmm... kinda.
I don't think you can use a literal sarissaphoros (top of page) in any terrain, however, that is not to say that a soldier that has the nomclature of 'sariossaphoroi' would not be able to be re-equipped to fight in a different style which could be used in different terrains. I understand that this is what Philip and Alexander did to make the phalanx more flexible.