Answer 1

dark/ ghost has no weaknesses.
bug/ steel has only one weakness and 10 resistances
dragon/ water only has a weakness to dragon
dragon/ steel has 12 resistances
normal/ psychic has only 2 weaknesses and ghost has no effect. This is the only combination of normal with another type that normal covers a weakness.
electric/ steel has 13 resistences
steel/ grass has 11 resistances and only2 weaknesses
poison/ dark has only a ground weakness
ground / water has only a grass weakness(credit to Pokemoning and mirkjani for those two)

Comments

these are only some. there are a lot.

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poison/ dark only has one weakness to ground

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Water/Ground has only one weakness to grass

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technically, dark/ghost does have a weakness...
Foresight + any fighting move=Dead dark/ghost pokemon

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No one uses foresight...
BTW, you wrote ground water only has water weakness when it should be grass

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i use foresight ingame to screw Cynthia over with my Lucario... i must be a no one... :/

but on the bright side, no one is perfect :D

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There, I fixed the ground/ water problem

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Also Electric is pretty good on it's own

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Yeah, but he said type COMBOS. Sorry for the caps. It's for emphasis

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Like Leboss said "No one is perfect" ;)

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he said???

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check a few comments back