Resists Rock, Ice, Electric, Psychic, Ghost, Bug, and Dark
Needs to be NU or below
Does not need weather to work well
No Pokemon resist all of those but one Pokemon that first comes to my mind is Bastiodon a Rock/Steel Type.
>Bastiodon (M) @ Leftovers
EVs: 252 HP / 4 Def / 252 SDef
Careful Nature (+SDef, -SAtk)
- Metal Burst
- Stealth Rock
There is nothing below the NU tier; NU means Neverused, so there isn't a tier that's lower than that.
Bastiodon (Rock/ Steel)
Probopass (Rock/ Steel)
They don't resist Electric, but are neutral to it.