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>The moves Hyper Beam and Giga Impact require a special type of energy that Pokemon build up naturally. However, this type of energy is the same as the type used to evolve. As such, Pokemon that still have yet to evolve commonly cannot use these moves, due to saving the energy for a potential evolution. After the Pokemon is fully evolved (or believes it is fully evolved, in the case of Pokemon like Golbat, Porygon2, and Rhydon), it will instead the energy it's built up to be able to use Hyper Beam and Giga Impact.
>As for Pokemon who can naturally learn these moves (like Axew and Klink), they have a natural excess of this evolutionary power, and can use it to learn Hyper Beam or Giga Impact, and still have enough left over to evolve.
