So, your Mega Altaria is VERY strange. Altaria-Mega is supposed to be a setup sweeper, (via Dragon Dance, not Cotton Guard) which gives him a niche in the UU metagame. However, if you just want to use a Cotton Guard Mega Altaria there’s really no point in just using a bulky Mega Ampharos or something instead. Here’s a more effective Mega Altaria set I’ve used myself before:
Altaria-Mega @ Altarianite
Ability: Cloud Nine—>Pixilate
Jolly Nature
EVs: 252 Spe/252 Atk/4 Def
- Dragon Dance
- Return
- Dragon Claw
- Earthquake
Description: So, I guess you could use Frustration to counter Ditto, but I’ve literally never seen Ditto in UU my whole 3 years of playing Pokémon I think you’re fine. Earthquake is for coverage against Electric types, and is especially useful against Mega Manetric (you outspeed him after one DD). Dragon Claw is sort of a filler, I almost never find myself using it as Return also hits super effective against other dragons anyways.
So, two status moves on the same Pokémon? You need to choose either Yawn + Stealth Rock, or Unaware Wall, but I’ll choose Unaware Wall for you because it fits much better on your team then a hazard setter. Here’s a Curse + EQ Quagsire
Quagsire @ Leftovers
Ability: Unaware
Relaxed Nature
EVs: 252 HP/252 Def/4 SpD
- Earthquake
- Scald
- Curse
- Recover
Description: Just your standard annoyer to switch in after you got OHKO’d by a setup sweeper.
I get that HP Fire is for Scizor, but that’s not going to help you much compared to this set:
Porygon2 @ Eviolite
Ability: Trace
Calm Nature
EVs: 252 HP/104 Def/152 SpD
IVs: 0 Atk
- Foul Play
- Ice Beam
- Toxic
- Recover
Description: Another standard Toxic Staller with a littlest bit of an offensive pivot.
Espeon doesn’t add much to your team, and you said you needed a solid Defog user. Here it is:
Latias @ Life Orb
Ability: Levitate
Timid Nature
EVs: 252 Spe/252 SpA/4 SpD
IVs: 0 Atk
- Defog
- Draco Meteor
- Psychic
- Hidden Power (Fire)
Description: So HP Fire is for Scizor, but if you’d like, you can switch it out for Thunderbolt, but I personally prefer HP Fire. (Thunderbolt would be for Azumarill). Speaking of which, be very careful with Azumarill. They can set up a Belly Drum and if you don’t OHKO them at 75% health, which you probably won’t, then you might get swept if your Auagsire isn’t fainted.
Your Gliscor is more of a defensive Gliscor than offensive, and if you’re going to run that you might as well just use Eviolite Gligar. Here’s a Gliscor that better utilizes his attack stat.
Gliscor @ Toxic Orb
Ability: Poison Heal
Jolly Nature
EVs: 252 Spe/252 Atk/4 HP
- Swords Dance
- Earthquake
- Facade
- Roost
Description: Roost may be swapped for Protect to scout out your opponent and to allow the Toxic Orb to kick in, but Roost offers faster recovery than Protect + Poison Heal stalling, so I went with Roost.
Rotom-Heat @ Firium Z
Ability: Levitate
Modest Nature
EVs: 252 HP/252 SpD/4 Spe
IVs: 0 Atk
- Overheat
- Volt Switch
- Will-O-Wisp
- Hidden Power (Ice)
Description: Bulky Attacker Rotom-H. Utilizes a Z Move, which your team is missing. Volt Switch and Will-O-Wisp are great utility moves. Not much else to say about this set.
And here is your slightly improved UU team. Thank you for your time.
