After thinking about it, I can deduce why ??? is so low, besides the point it's so mysterious that it doesn't even have letters, and that it's only related to Curse (???-type until Gen. V, where it was made Ghost), Eggs (they were ???-type in Gen. III), Weather Ball (it's ???-type if used during Shadow Sky, Arceus (it does have a ???-type form, but it cannot be used without hacking), and Roost (in Gen. IV, it made the use ???-type after using; this was changed to Normal-type in Gen. V). It's the fact that it was removed in Generation V. Unfortuantly, it is no longer a type.So now here we are at 36. Yet ???, Electric, Ground, Normal, and Rock still have 0. Any comments on that?