if your game area is empty i.e. no obstacles present, you can simply utilize only tossing from the few flocking rules, i.e. if the 2 enemies (or any number of enemies) are becoming too close to each other you should add a "force" pointing away from each other, the stronger the closer they are, or instead of this force modify their movement by a vector pointing in opposite directions to smoothly keep them away from each other. in case of many enemies you should probably define a priority order how tossing is calculated.
finally in 3DGS you have there the push event in case of when collision happens even if you use some kind of avoidance it is good to handle it for safety...