Pokemon Type Chart (Gen 1)

Note: There is a glitch in the generation 1 games where dual typed pokemon recieving damage may display the wrong effectiveness message but they will still take the proper amount of damage.
Attack TypeNormalFightingFlyingPoisonGroundRockBugGhostFireWaterGrassElectricPsychicIceDragon
Normal1x1x1x1x1x1/2x1x0x1x1x1x1x1x1x1x
Fighting2x1x1/2x1/2x1x2x1/2x0x1x1x1x1x1/2x2x1x
Flying1x2x1x1x1x1/2x2x1x1x1x2x1/2x1x1x1x
Poison1x1x1x1/2x1/2x1/2X2x1/2x1x1x2x1x1x1x1x
Ground1x1x0x2x1x2x1/2x1x2x1x1/2x2x1x1x1x
Rock1x1/2x2x1x1/2x1x2x1x2x1x1x1x1x2x1x
Bug1x1/2x1/2x2x1x1x1x1/2x1/2x1x2x1x2x1x1x
Ghost0x1x1x1x1x1x1x2x1x1x1x1x0x1x1x
Fire1x1x1x1x1x1/2x2x1x1/2x1/2x2x1x1x2x1/2x
Water1x1x1x1x2x2x1x1x2x1/2x1/2x1x1x1x1/2x
Grass1x1x1/2x1/2x2x2x1/2x1x1/2x2x1/2x1x1x1x1/2x
Electric1x1x2x1x0x1x1x1x1x2x1/2x1/2x1x1x1/2x
Psychic1x2x1x2x1x1xx1x1x1x1x1x1/2x1x1x
Ice1x1x2x1x2x1x1x1x1x1/2x2x1x1x1/2x2x
Dragon1x1x1x1x1x1xx1x1x1x1x1x1x1x2x