To counter a Poison-type Pokemon, you can use the following types of Pokemon or moves:

• Ground-type Pokemon or moves: Ground-type moves are super effective against Poison-type Pokemon, making them a good choice to counter them. Powerful moves like Earthquake and High Horsepower can quickly destroy a Poison-type.

• Psychic-type Pokemon or moves: Psychic-type moves are also super effective against Poison-type Pokemon. However, Psychic-type Pokemon typically excel as Special Attackers, while Ground-type Pokemon are predominately physical attackers.

• Ghost-type Pokemon or moves: Ghost-type moves are not very effective against Poison-type Pokemon, but Poison-type Pokemon are vulnerable to Ghost-type moves.

• Rock-type Pokemon or moves: Rock-type moves are not very effective against Poison-type Pokemon, but Poison-type Pokemon are vulnerable to Rock-type moves.

• Steel-type Pokemon or moves: Steel-type moves are not very effective against Poison-type Pokemon, but Poison-type Pokemon are vulnerable to Steel-type moves.

Its important to note that the effectiveness of these types of Pokemon or moves will depend on the specific Pokemon you are facing, as well as its stats and moveset.