imo if
ANY mech was introduced to PS2 it would have armor lighter than an lightning but higher than an ATV with weaponry only good enough against infantry but if infantry with AV show up they must flee. speed wise it would be as fast as an lightning or slightly slower but more maneuverable than either the lightning or ATV. another other possibility would make them unique to an single continent that has an landscape not made for tracked vehicles in mind.
NO FLIGHT MECHS!!!!!!!
either way i dont really care if an mech is in the game or not. it be interesting yes but whatever