almost everything
Ground type is the only type that is super-effective against ground Water, Flying, Dragon and Electric are poor against it
Rock type Pokemon are strong against flying, ice, bug and fire type Pokemon.
Ground type attacks are strong against Electric type Pokemon (super effective--2X damage), and everything except Flying, Steel, and Electric works normally against them (effective--1X damage). Flying, Steel, and Electric moves are not very effective against electric (half damage). Also, if your Pokemon is the same type as the type of the attack it is using, the attack power increases by 50% (Same-Type Attack Bonus). So, the absolute best thing you could do against an Electric Pokemon is have a Ground-type Pokemon attack with a strong Ground-type move, such as Earthquake, Dig, or Drill Run.
Since Charizard is a Fire/Flying-type, it can easily knock out a Grass, Bug, Steel, Fighting, and Ice-type Pokemon, if it has both a Fire and Flying-type move like Flamethrower and Fly.
Ice-type Pokemon are strong against Ice-type moves. On the offensive side, it can greatly harm a Grass, Ground, Flying, and Dragon-type. (2x the damage)
Fighting types are weak against psychic and flying types.
Flying, Poison, Bug, Fire, and Ice type moves are strong against a Grass type Pokemon.
Rock, fire, and flying type are strong against the bug type.
Fighting type Pokemon are weak exist Flying and Psychic.
Flying type Pokemon are good against normal Pokemon.
Ground type is the only type that is super-effective against ground Water, Flying, Dragon and Electric are poor against it
Rock type Pokemon are strong against flying, ice, bug and fire type Pokemon.
Machamp is a Fighting type pokemon which are weak to Psychic, Fairy, and Flying type moves.
Hitmontop is a Fighting Type pokemon which are weak to Psychic, Fairy, and Flying type moves.
Rock, electric and ice are super effective against flying type pokemon.
* Electric * Ice * Rock Go visit http://bulbapedia.bulbagarden.net/wiki/Type_chart_%28Generation_II-present%29
Ice-type Pokemon are resistant to only Ice-type attacks. In offense, Ice-type Pokemon can do 2x the damage to Grass, Ground, Flying, and Dragon-type Pokemon.