[quote=@Ryuzaki]
<Snipped quote by Joshua Tamashii>

Pokémon learn moves through leveling and practice, hence why a leveling system is in place. Your pokemon should be around the level it needs to be to use the moves it does.
[/quote]

While that level of freedom is nice, imagine having a pokemon that knows it's entire move list from levels, HMs, and TMs. That level of adaptability could be bothersome, don't you agree?