I'd rather just use Sludge Bomb if you're going that route tbh. The spread damage reduction hurts when you need to hit a Fairy, and odds are the opponent has something else on the field that really gives no fucks about Sludge Wave. Rock, Ground, Steel, and Poison all resist it, and there's really only two reasons not to spam Draco:
1: Can't switch, and/or it'd be a net loss to cripple yourself over the opponent,
2: Fairy type.
Considering our omnipresent Sylveon, this is also important to note:
252+ SpA Choice Specs Adaptability Dragalge Sludge Wave vs. 252 HP / 0 SpD Sylveon: 176-208 (87.1 - 102.9%) -- 12.5% chance to OHKO
252+ SpA Life Orb Adaptability Dragalge Sludge Wave vs. 252 HP / 0 SpD Sylveon: 151-182 (74.7 - 90%) -- guaranteed 2HKO
252+ SpA Choice Specs Adaptability Dragalge Sludge Bomb vs. 252 HP / 0 SpD Sylveon: 224-264 (110.8 - 130.6%) -- guaranteed OHKO
252+ SpA Life Orb Adaptability Dragalge Sludge Bomb vs. 252 HP / 0 SpD Sylveon: 198-234 (98 - 115.8%) -- 87.5% chance to OHKO
You kind of need to OHKO it, too. Because it 2HKO's you back and its faster.
252+ SpA Choice Specs Pixilate Sylveon Hyper Voice vs. 252 HP / 0 SpD Dragalge: 93-109 (54 - 63.3%) -- guaranteed 2HKO
Also adding that Wide Guard isn't exactly rare now thanks to Sylveon and Lando-T, its just a lot safer to Sludge Bomb. Plus, triple the Poison chance to add nice chip damage to things like Cresselia.
But on a different note... is Reflect Type Latias a thing? I know it removes STABs, but on a supportive set, well, a Ghost/Steel type with Levitate could be pretty funny. Or copy a Rotom-W, Raikou, Mega Manectric, Heatran, Entei, etc.
Shame that Latias probably has the most horrific 4MSS I've ever dealt with.