Yea, no. We have yet another tragic case of overspecialization here, and to be honest full-on RestTalk shuffling hasn't been exactly cute or viable for the last few years due to how exploitable the strategy tend to be (unless you're gen V Black Kyurem). Since this thing lacks decent recovery, it's easy to defog hazards now, and the thing is vulnerable to many many many weaknesses that dedicated shuffling be unsuccessful 70%+ of the time, I think it's better to call it quits on the purely defensive front and follow Hyreigon/Goodra's footsteps.
Guzzlord @ Choice Specs / Assault Vest
Ability: Beast Boost
EVs: 128 Def / 252 SpA / 128 SpD
Modest / Quiet Nature
- Draco Meteor
- Dark Pulse
- Sludge Bomb / Dragon Tail
- Fire Blast / Dragon Tail
Okay, you got some utterly unremarkable but usable offensive stats, you're slow as Lady Gaga's current career and you have a booty and HP stat so big it makes Tyler Perry's Madea suit cry. So, if you don't want to be dead weight, max our your offense, invest in the defense stats (instead of HP for optimal defense gains) and strut your stuff like slow attacker number 2342346. Voila, you're Shaq now. If you specifically want Guzzlord to switch and retaliate against one specific type of attack (special or physical) over another, though, feel free to invest fully in the respective defense stat since that VASTLY improves the stat (See: Chansey).
So as
Clair said, you'll be expecting Specs Guzzlord to hit slightly less harder than Hydreigon; fortunately, due to Dark Pulse's coverage and Draco Meteor's immediate power you'll still be able to nuke stuff pretty hard. The draw here is its ability to tank attacks; with the EV spread, you're approximately as bulky as 252/252+ Druddigon and standard Stealth Rock Clefable, so it doesn't go down easy. Alternatively, it can don an Assault Vest ala Goodra and mess up conventional switch play when people think it's safe to go in after Draco Meteor. Vest set is best used somewhat early when you have rocks and/or toxic spikes set up. Some calcs showing its bulk (though I doubt it'll dissuade anyone from using Hydreigon instead):
252 Atk Life Orb Bisharp Iron Head vs. 0 HP / 128 Def Guzzlord: 224-265 (36.9 - 43.6%) -- guaranteed 3HKO
252 Atk Life Orb Bisharp Iron Head vs. 0 HP / 0 Def Hydreigon: 181-214 (55.6 - 65.8%) -- guaranteed 2HKO
252+ Atk Choice Band Tapu Bulu Wood Hammer vs. 0 HP / 128 Def Guzzlord in Grassy Terrain: 328-387 (54 - 63.7%) -- guaranteed 2HKO (can take one hammer, retaliate with Fire Blast or Sludge Bomb)
252+ Atk Choice Band Tapu Bulu Wood Hammer vs. 0 HP / 0 Def Hydreigon in Grassy Terrain: 264-311 (81.2 - 95.6%) -- guaranteed 2HKO (gets KO'd after rocks or a round of LO damage)
252 Atk Life Orb Technician Breloom Mach Punch vs. 0 HP / 128 Def Guzzlord: 346-408 (57 - 67.2%) -- guaranteed 2HKO
252 Atk Life Orb Technician Breloom Mach Punch vs. 0 HP / 0 Def Hydreigon: 281-330 (86.4 - 101.5%) -- 12.5% chance to OHKO
184 SpA Life Orb Latias Draco Meteor vs. 0 HP / 128 SpD Assault Vest Guzzlord: 421-499 (69.3 - 82.2%) -- guaranteed 2HKO (gets KO'd w/o)
184 SpA Life Orb Latias Draco Meteor vs. 0 HP / 0 SpD Hydreigon: 507-601 (156 - 184.9%) -- guaranteed OHKO (with an assault vest it still gets KO'd)
+1 252 Atk Life Orb Gyarados Bounce vs. 0 HP / 128 Def Guzzlord: 356-421 (58.6 - 69.3%) -- guaranteed 2HKO (retaliates w/ Dragon Tail or specs meteor = 86.4 - 101.8%)
+1 252 Atk Life Orb Gyarados Bounce vs. 0 HP / 0 Def Hydreigon: 286-339 (88 - 104.3%) -- 31.3% chance to OHKO
And yeah, guess that's the best it can do since it learns jack shit for healing or boosting (at least Curse, christ).