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Deals a set amount of damage equal to a random value between 0.5x and 1.5x the user's level, rounded down, but not less than 1 HP. Does not take type resistances or weaknesses into account, but cannot hit Dark-types. The calculation for the amount of damage dealt is as follows, where where X is a random number from 0 to 100:
Base Power = (user's level) * (X+50) / 100
This move seems like it would function as a decent alternative to Seismic Toss or Night Shade for Pokemon that do not have those moves. The problem is that every Pokemon that gets this move has a decent enough Attack or Special Attack stat (relative to its tier) to use other damaging moves. Plus, a 50-150 damage range is rather unpredictable compared to the stability of Night Shade and Seismic Toss.
Psychic is a much more powerful option available to every Pokemon that learns Psywave.