Leech Seed is kind of superior in this case, why does it matter that you want to hit Ghosts? Breloom has Leech Seed and Substitute, and enough speed to outstall things like Rotom-H (which bulky versions have almost no speed) with SubSeed, Leech Seed, Sub, until it dies while Breloom remains healthy. If you're going to put it on Gengar terms, he has a Scizor meant for taking Special Attacks, don't see the problem. So defently keep Leech Seed, well the current set.