>>55647240If you think of moveslots less as the literal ability to punch something really fast and more in terms of the Jack Vancian method of dedicating part of your skull to keeping incredibly powerful elemental energy in your head without having an aneurism, then you'll see the whole Type system really start to click.
Essentially, each Type is a type of energy, and each Move is a pattern or wavelength of that energy. A Heatran and a Happiny can both use Fire Blast by tapping into the same wavelength, but one is obviously going to be much more potent a result than the other. Some mons instinctually pick up on these wavelengths, while others need to be instructed on how to harness them. Like, say, instructed through an audio recording. An audio recording played on a disc. But maybe the disc is fragile and can only maintain the integrity to play that wavelength once. See where I'm going with this? Without a little boost from a performance-enhancer to sharpen the mind, a user can only channel that wavelength so many times before it's expended and needs to be recharged with a good sleep or meditation--this is how Fire Blast and Ember have different power pools despite drawing from the same base element.
A Water-Type Attack isn't just the blunt force trauma of getting blasted by a fire hose, it's also suppressing an opponent's ability to channel their own energy effectively until they're physically incapable of battling anymore. Dark-Type attacks aren't just effective against Psychic-Types because it hurts to have your hand bitten by a big rat or dog, but because Dark-Type energy not only shuts down an opponent's ability to channel Psychic Energy, but completely nullifies it too. Forgetting Bite doesn't mean you forget how to chew your food, you just unlearn how to focus Dark energy around your teeth to pierce through steel or tear into the ethereal.