-Types can have no effect on another (=), double damage (+), or half damage (-). Also note that if a Pokemon is a certain type, and it attacks with the same type of attack, it will inflict one-half extra damage on the opponent (before type confliction).
-Below is a list of types and how they fare against another. Notice that the topic type is the type you are using. Also, if two types will not have any difference in effect, it will not be listed.
Normal [Regular] -Rock, =Ghost, -Steel
Fire [Special] -Fire, -Water, +Grass, +Ice, +Bug, -Rock, -Dragon, +Steel
Water [Special] +Fire, -Water, +Grass, +Ice, +Bug, -Rock, -Dragon
Electric [Special] +Water, -Electric, -Grass, =Ground, +Flying, -Dragon
Grass [Special] ?Fire, +Water, -Grass, -Poison, +Ground, -Flying, -Bug, +Rock, -Dragon, -Steel
Ice [Special] ?Fire, -Water, +Grass, -Ice, +Ground, +Flying, +Dragon, -Steel
Fighting [Regular] +Normal, +Ice, -Poison, -Flying, -Psychic, -Bug, +Rock, -Dragon, -Steel
Poison [Regular] +Grass, -Poison, -Ground, -Rock, -Ghost, =Steel
Ground [Regular] +Fire, +Electric, -Grass, +Poison, =Flying, -Bug, +Rock, +Steel
Flying [Regular] ?Electric, +Grass, +Fighting, +Bug, -Rock, -Steel
Psychic [Special] +Fighting, +Poison, -Psychic, =Dark, -Steel
Bug [Regular] ?Fire, +Grass, -Fighting, -Poison, -Flying, +Psychic, -Ghost, +Dark, -Steel
Rock [Regular] +Fire, +Ice, -Fighting, -Ground, +Flying, +Bug, -Steel
Ghost [Regular] =Normal, +Psychic, +Ghost, -Dark, -Steel
Dragon [Special] +Dragon, -Steel
Dark [Special] +Ghost, -Steel
Steel [Regular] ?Fire, -Water, -Electric, +Ice, +Rock, -Steel