electric,fire and rock
Electric, rock and ice type moves.
ground types
There are a few electric type Pokemon you can get in ruby and sapphire and emerald like Electrike you can find a lot of them in New Mauville you can find Magnemite and Voltorb. Other electric types you can get are Pikachu, Mareep.
yes they do i used it
The rock/sand ones, they are immune to electric attacks.
Since there water type trainers use electric types or grass type pokemon.
Mostly water types but he has a Kingdra so watch out.
Maybe depends on what you have dark types are good against the leader.
Ground is currently the only weakness of Electric. Rock types, Dragon types, and Pokémon with the abilities Lightningrod and Volt Absorb are good as well.
electric and grass are all I can think of
Grass and Electric types