Along with Electric, run Dugtrio. It takes off most things that can take it's electric attacks, like A-Marowak, Magnezone, lol Lanturn and such (that can resist the Boltbeam combo).
I also enjoy using it with Nasty Plot on the last slot (along with screens), sometimes it's well worth, mainly against some ground pokes not weak to Ice (they come in on conversion, easily survive the attack and now their ground attacks are SE against you; with NP your Ice Beam will 2HKO all of them and no weakness to ground).
Marowak-A can't be trapped as it is a ghost type.