I donīt know if this helps but hereīs how I deal with those flying Geonosians:
Whenever you see one coming at you (if itīs flying), take a step back. That way, they will land right in front of you. One well aimed melee attack and splat, they are dead.
If they are not flying, keep an eye on a the reach they have with their spear. Stay away and try to shoot em or dodge their attack and melee em.
Always a good thing to do as told is to assign some squad mates to a sniping position.