Change your preferences here.
Deals damage and has a 30% chance of badly poisoning the target.
Poison Fang is a poor move. While it has a high chance of badly poisoning the target, its bad distribution and horrible coverage cause Poison Fang to fall into obscurity. Even as a STAB move, the underwhelming power that Poison Fang provides is far from desirable, especially when taking into consideration that the Pokemon most able to use it generally have other options for a physical Poison-type move, such as Cross Poison and Poison Jab. In addition, barring Arbok and Seviper, all Poison-type Pokemon that learn Poison Fang have a secondary type, and these Pokemon almost never use their Poison-type STAB moves due the high quantity of Pokemon that either resist or are immune to Poison-type moves. Overall, if you want to use a physical Poison-type move, don't bother with Poison Fang, as Cross Poison, Poison Jab, and even Gunk Shot outclass it. If you want just to inflict toxic poison, Toxic is much more reliable.
Poison Jab is a more powerful option.
Gunk Shot is a much more powerful option, but has lower accuracy.