>>55646575A lot of Normal type moves are also known by default by all Pokemon or all Pokemon that fit into a certain category. For example, basically any Pokemon can Tackle, but only Pokemon with sharp claws can Slash. This doesn't apply to "upgraded" moves such as Giga Impact, because those would take a lot more effort and weight to pull off. As a result, most Pokemon know at least four moves from even Level 1. Crunch is a special case, because since it's a Dark type move, I imagine that the user imbues Dark energy into its jaws before Crunching, and it would have to be trained to do that. It would only be inherent to certain Dark types like Houndoom.
Oh, and if you think the example with Kingdra is ridiculous, that's literally just its TMset in the current generation.
