You complain about bug and ice but poison is actually the worst type.

>primarily a secondary type because theres no poison weather, strategy, stats etc.
>only hits grass for super effective
>weak to 2 of the 5 most common attacking types psychic and ground
>primarily exist to be used by bad team
>only real advantage is poison
>toxic tm gives every pokemon in the game poison
>steel is immune to you

I'll admit you can name like 5 good poison pokemon but none are using poison moves. Poison primarily acts as a way to give good mons like naganadel and toxapex weaknesses, and not much else.

>is good against fairy
No ones using poison attacking moves