I really like Vileplume, however since Gholdengo is inmune to Leech Seed, Stun Spore, Sludge Bomb and especially Strength Sap, facing one means you play with 5 Mons. At least Corviknight can escape, Fraudmory can put a Spike and Amoonguss learns Foul Play, Vileplume however its entirely walled. Yes, it will be able to switch into Waterpon, Rillaboom and something, but as long as Gholdengo is alive, Vileplume won,t be able to use ANY move.
Therefore, Vileplume has 2 options to avoid crazy match-up fishing: 1. Run it with 5 Mons that beat Gholdengo very badly (Samurott, Moltres, Tera Water Garg, Payback offensive Ting-Lu and Gambit as an example), or 2. running Tera Blast (Dark and Fire being the best ones). Its an unfortunate case of a Pokemon being made entirely unviable by just one single Mon existing.