I have several gelatinous friends
A stall team built around the double Regenerator core of physically defensive Foongus and specially defensive Mareanie. Hisuian Qwilfish and Skuntank keep the team from folding to Psychic-type attacks, while Paldean Wooper adds a Ground-type and a rocker. Acid Armor Swalot rounds out the team as a win condition.
Mono poison has some glaring weaknesses, particularly the complete absence of hazard control options. The team also struggles to switch into strong Normal- and Ground-type attacks (I considered running Gastly but it's not switching into anything other than an immunity). But with a little matchup luck, you should be able to win some games.