>>39381942Normal isn't typeless, because it still interacts with other types. Typeless would mean it's neutral against everything.
And that kind of thing actually does exist in the games, it's just very rare. For example, if a Fire-type uses Burn Up, it becomes typeless. It resists nothing and is weak to nothing, and doesn't get STAB on anything.
So the games are designed to handle the concept of typelessness, but they didn't utilize that to make "Type:Null" an actual typeless Pokemon, which is disappointing.