Grass refers to a specific group of plants, not to all plants in general. Ghost refers to a specific paranormal being, not to just anything weird. Steel is a particular alloy, being distinct from iron, and there are no steel metors to mash with, nor are bullets made from steel. Magma and lava are not fire. Etc etc etc.Bug refers to a certain set of species, makes me think of insects, not arachnids.
Game Freak do need to fix the heights and weights I reckon. Wailord is a prime example - estimates of its density are about 1.3 kg/m^3. Water is 1000 kg/m^3. So there's no way Wailord could dive, or even appear to swim normally - it would sit on top of the water with hardly any of its body submerged. Indeed there's margin in the estimate for Wailord to be lighter than air, and thus float like an airship. I know Pokemon's not realistic, but it shouldn't be that ridiculous.