Here’s all the Pokémon I found that learn Toxic and Will-O-Wisp:
- Gengar Line
- Weezing Line(including Galarian)
- Trevenant
- Salazzle Line
None of these Pokémon our listed in Smogon’s list of viable Gen 9 OU doubles. So these Pokemon aren’t viable. Another thing, doubles is an offensive and fast-paced game.
Passive damage is usually ineffective because the game goes by too fast for it to take its toll.
While you might face opponents packing stall or similar defense-oriented teams in singles, you'll find none of those in the Doubles metagame. In Doubles, playing passively or defensively and hoping to win through passive damage is ineffective because such a style can easily get overrun when dealing with two strong attackers at a time. In this kind of metagame, there are only attackers, the ones who lay the hurt on foes, and supporters, Pokémon that help the attackers do their jobs through numerous methods such as redirection support or Speed control.
Source Hope this helped!
