I'm glad you decided to post your team here. :D
I wouldn't know what to do with Miltank anyway. It looks like a solid set though, from everything I understand about Miltank as it is. I've never seen one with Stealth Rock though, but I can't come up with a reason why it shouldn't work as a lead. I'll follow up with this if I find the time.
Decent Nasty Plot set. I encourage you to try out Taunt over HP [Grass]. It will allow Houndoom to chew through walls and counter common Baton Passers. Also, a Passho Berry will help Houndoom absorb Water attacks from powerful Water types like Milotic, Empoleon, and Suicune.. However, the combination of HP [Grass] and the Passho Berry may be a more situational, but potent pairing, considering you would be 2HKOing the aforementioned Pokemon (save Empoleon).
Considering how the rest of your team works, I think you may get more out of Cohagrigus' standard bulky Ghost set.
Cohagrigus @ Leftovers
252 HP / 136 Defense / 120 Special Defense
Bold [+Defense; -Attack]
- Shadow Ball / Hex
Instead of countering like your previous Cohagrigus set was made for, this one focuses more on being a defensive pivot in battle. The set is more or less self explanatory. Haze will shut down any defensive stat boosting Pokemon. Will-O-Wisp will lock up any heavy physical sweepers and work them down while you absorb their attacks. Rest is, sad to say, your only credible form of Recovery. And Shadow Ball is the best STAB move you could ask for. Alternatively, Hex can be used due to its useful 100 Base Power when the opponent is afflicted with a status condition. So, that should also be considered. However, at the end of the day, Cohagrigus has more competition in terms of usage against Eviolite Dusclops than anything else.
I don't know much about Musharna, sorry to say. But, I do think there are better Psychic types / Special Walls at your disposal to choose from. I mean, isn't Cresselia in UU?
Cresselia @ Leftovers
252 HP / 252 Defense / 4 Special Attack
Bold [+Defense; -Attack]
- Thunder Wave / Psychic
- Ice Beam
- Moonlight / Rest
Okay, so, because of Cresselia's amazing bulk and supportive movepool, it can really be an asset in battle. Reflect is going to half the damage taken from Physical Attacks, something that Cresselia is going to love you for. Thunder Wave punishes anything that tries to set up against it, while Psychic can be used as a solid STAB attack to hit the Fighting types you will encounter. Both have excellent results, but the usage depends on the situation. Ice Beam hits Dragons for super effective damage and will discourage them from switching in on Cresselia. Finally, it's really a toss up between Moonlight and Rest. So, whichever you prefer is optimal. Moonlight gets the boost in the Sun and the hit in Sand, while Rest puts you to Sleep. Both have advantages and shortcomings.
In my opinion, the way your running Sceptile is a fierce understatement of what it can really accomplish. Sceptile holds the bar as the fastest innate Sub+Seeder in the game regardless of Whimsicott). And unlike Whimsicott, Sceptile actually have some offensive prowess to speak of. So, here's what I recommend.
Sceptile @ Leftovers
252 Special Attack / 28 Special Defense / 228 Speed
Timid [+Speed; -Attack]
- Leech Seed
- Giga Drain
- Hidden Power [Fire]
The essence of this set lies in the Subsitute + Leech Seed combination. Where, ideally, you set of Leech Seed on the opponent and hide behind multiple Substitutes to stall out for Giga Drain and Leftover recovery. HP [Fire] will hit most that are immune to Leech Seed and grant you general 2HKOs on common Steel types. However, I do understand you wanting to take advantage of Sceptile's natural Speed with an offensive set. If so, I recommend Leaf Storm / Focus Blast / Hidden Power [Ice / Fire] / Dark Pulse with a Timid [+Speed; -Attack] or Hasty [+Speed; -Defense] nature and 4 HP / 252 Special Attack / 252 Speed with a Life Orb.
I already went over Lapras in your previous thread. But for the sake of consistency, I will just c+p it in here too.
Lapras @ Leftovers / Life Orb
252 HP / 4 Defense / 252 Special Defense
- Toxic / Ice Shard
If you're not going to use Dragon Dance than I highly suggest giving Lapras Ice Shard to make up for the hit in Speed. After a few Curse boosts, Lapras becomes very difficult to take out, and has such reigned as a bulky sweeper in the lower tiers. Dragon Dance is extremely viable, especially with the ever devastating BoltBeam combo. However, I prefer the Curse set simply because it has more utility and there are better sweepers out there. Since Lapras doesn't exactly have the best physical move pool out there, Return can be used to hit Gyarados and Rotom-W, both of whom resists Waterfall. Bulldoze can be used to hit Empoleon, but has little usage beyond that. So STAB Waterfall and STAB Ice Shard are your best offensive tactics. EVs maximize Lapras' special bulk giving it a healthy defensive core.
Finally, there are some few problems your team faces as a whole. I don't know how prevalent they are in UU nowadays, but I see Hitmontop, Rhyperior, and basically anything with a strong Fighting core giving this team a hard time. Luckily, you do have the immunity in Cohagrigus and the resistance in Musharna. But, they can easily give a good hit to Houndoom, Miltank, and Lapras. Also, Flygon (still UU?) and Altaria might cause problems with you considering that every Pokemon on your team takes neutral damage from Dragon Type attacks. Beyond that, I would say Charizard is a threat only because it's capable of running both Dragon Pulse and Focus Blast but, I don't think anyone does that. lol Anyway, I hope my rate helped a bit. I wish I had more to say about UU teams but unfortunately I'm not fluent in that tier. I'll try to do some follow up work on Miltank and offer you something better than what I said.