That said, getting Trick Room support and a safe switch-in is tricky, but doable. Liquid Ooze plus Curse and Block (4th Gen Tutor) is a great way to ruin a Physical Attacker+Seeder/Drainer that somehow isn't taking the full brunt of your STAB (like if you can't hit the broad side of a Snorlax due to inaccurate Moves or if they are a Seeder Ferrothorn).
Getting Swalot in at all is high-risk. So many Pokemon know Psychic or Ground Moves that any Poison Type has issues.
For a safe switch-in on EQ, you'll need to work with an Air Balloon in Singles or an Imprison+EQ Pokemon Partner in Doubles/Triples. Not many Pokemon can have both Imprison and EQ to help - Stantler, Bronzor, Bronzong, Landorus, Dusclops, and Dusknoir. Stantler and Bronzor/Bronzong would be best since they can learn Psychic Moves and use them fairly well (Stantler's Zen Headbutt and Bronzor/Bronzong's Psychic).
A "safe" Doubles/Triples Partner for Swalot:
Quiet, 252 to both defenses, 6 to HP
Red Card/Leftovers/Wise Glasses
Imprison, EQ, Psychic, Hidden Power (Dark)
Triples Partner for Swalot & Bronzong:
Impish, same EVs as Bronzong
Block (4th Gen), Recover, Pain Split, Rock Slide
Position - Center
Basically, Block High-HP opponents or ones that can't handle super-effective Moves too well, Imprison immediately and go for broke with Swalot. As for a Swalot for this Triple set, try this:
Careful/Calm, 252 to HP, 160 to Sp.Def, rest to Defense
Black Sludge/Rocky Helmet
Careful - Gunk Shot, Ice Punch (4th Gen Tutor), Thunderpunch (4th Gen Tutor), Seed Bomb (4th Gen Tutor)
Calm - Sludge Bomb, Ice Beam, Shock Wave (4th Gen TM), Giga Drain (4th Gen TM)