BRIEF:

Ogre -> Mence

Khan -> Ho-oh

Reasons: Original team was weak to Ekiller, Salamence and Ho-oh.

Changing Ogre to a DEFENSIVE Mega Salamence gives an Ekiller check, a Mence phaser and a Ho-oh switch in.

Mence meant no more Khan, Ho-oh is added so you aren't 6-0d by CM Arc Forms, a strong physical attacker to finish Xerneas and a win-con vs stall or balance. Also gives insurance against Darkrai. Ho-oh also patches up the Block Geoxern weakness since Klefki lacks Heal Block.

NEW TEAM:

Arceus-Dark @ Dread Plate
Ability: Multitype
EVs: 248 HP / 8 SpA / 252 Spe
Timid Nature
IVs: 0 Atk
- Judgment
- Calm Mind
- Refresh
- Recover

Groudon-Primal @ Red Orb
Ability: Desolate Land
EVs: 248 HP / 252 SpD / 8 Spe
Sassy Nature
- Precipice Blades
- Lava Plume
- Roar
- Stealth Rock

Klefki @ Leftovers
Ability: Prankster
EVs: 248 HP / 8 Def / 252 SpD
Careful Nature
- Spikes
- Play Rough
- Thunder Wave
- Toxic

- 2 Fairy checks to go with Darkceus patches up the weakness.

Salamence-Mega @ Salamencite
Ability: Aerilate
EVs: 248 HP / 204 Def / 56 Spe
Impish Nature
- Body Slam
- Dragon Tail
- Refresh
- Roost

- Gives a more reliable check to things like Mega Salamence, Ho-oh and Ekiller. Refresh is so you can recover from burns from Ho-oh, and not get owned by Toxic. Body Slam is cool to spread Para. DTail is necessary to phase so you don't get set up on.

Ho-Oh @ Life Orb
Ability: Regenerator
EVs: 252 Atk / 4 Def / 252 Spe
Adamant Nature
- Brave Bird
- Sacred Fire
- Earthquake
- Roost

- Patches up CM Arc weakness, Block Xern weakness, and gives insurance against Darkrai. Also has good offensive synergy with Darkceus, as it thrashes Fairies, while Darkceus can set up on Ho-oh checks like Waterceus etc.

Latias (F) @ Soul Dew
Ability: Levitate
EVs: 212 HP / 120 SpA / 176 Spe
Timid Nature
- Draco Meteor
- Psyshock
- Defog
- Roost

Replaced Latios as better Ogre check and Defogger.

SUMMARY:

- Replaced Khan as it provided no real defensive synergy, and lacked real reason for helping on the offensive side.

- Replaced Ogre with Mence for better checks to strong physical attackers.

Top Threats and how you check them:

P-Don - Mence, Latias

Xerneas - Klefki, PDon, Ho-oh

Ekiller - Mence, Darkceus can live a hit and finish off.

Darkrai - Klefki, Ho-oh

Ho-oh - Mence

Salamence - your own Mence, P-Don with Roar, Klef with TWave.

Things to watch out for:

Ekiller setting up on -2 Lati.

Ho-oh still somewhat threatening as Mence can get overwhelmed, but a Ho-oh weakness is an inherent weakness when building with Darkceus as you take up the Arceus slot so you can't use Water or Rock. To patch up the issue, you can try Stone Edge on PDon over Lava Plume, DTail over Roar could also help with checking Mega Salamence, and annoys the Lati twins.

Fine otherwise.