Sometimes, move ideas do get turned down. Any of the following can make a move ineligible for inclusion in PF's archive:

1. Too strong an attack New moves should probably not be stronger than HYPER BEAM, and definitely should not be stronger than EXPLOSION. If it's in that range, or is a one-hit KO, there should also be a downside to using it, such as HYPER BEAM's loss of the next turn, the horrible accuracy of all one-hit KOs or EXPLOSION's...well, we all know what EXPLOSION does.

2. Too similar to an existing move Consider carefully the effect of your move. If it does the same thing, or very close to the same thing, as an existing move, there should be a good reason for the additional move, such as Exeggcute learning BARRAGE because they don't have the limbs to learn FURY ATTACK (which is identical to BARRAGE in all but name.)