In Generation 5 which Pokemon from the other generations do you expect to see. . .

once by dark, once by psychic.

Come again?
Dark attacks Dark = .5
Dark attacks Psychic = 2
Combined: 2 * .5 = 1

Psychic attacks Dark = 0
Psychic attacks Psychic = .5
Combined: 0 * .5 = 0

Come again?
Dark attacks Dark = .5
Dark attacks Psychic = 2
Combined: 2 * .5 = 1

Psychic attacks Dark = 0
Psychic attacks Psychic = .5
Combined: 0 * .5 = 0

...
Use a bug move on a dark type. its super effective.
Use a bug move on a psychic type. its super effective.

Pure dark and pure psychic are weak to bug. Weak, Normal, Half, Nul is my terminology for effectiveness.
Both pure types are weak once. combined, theyre double weak, or twice weak.

Oh, you worded it funny. I thought you were saying it was 4x weak to Bug and 2x to Psychic and Dark. (I function with a ratio. Numbers are fun like that.)

Oh, you worded it funny. I thought you were saying it was 4x weak to Bug and 2x to Psychic and Dark. (I function with a ratio. Numbers are fun like that.)

to each their own. but i figure Weak -> Normal -> Half -> Nul works in place of the longer/official variation.

[COLOR="Magenta"]I'm banking on some Luvdisc action.

Its evolution BEAST. Yes. I want that.

[/COLOR]