Clefable @ Leftovers
Ability: Magic Guard
EVs: 252 HP / 172 Def / 84 SpD
Calm Nature
- Stealth Rock
- Soft-Boiled
- Moonblast
- Fire Blast
As everyone before me has noted, the team needs Stealth Rock. I also noticed that the team relies on Magneton to take powerful Dragon-type attacks from the likes of Latios, and that won't do - Draco Meteor does more than 75% to Magneton, HP Fire has a good chance to OHKO, and Earthquake Latios gives Magneton even more headaches. Clefable fixes all that and takes on Latios and other Dragons fairly easily.
But that's not all! Clefable also eases this team's worries against things like Mega Sableye, who aside from Clefable only really needs to worry about Draco Meteor from Latias, and can burn Pinsir. Furthermore, with Fire Blast, Clefable acts as an effective lure and a secondary method of removing the Steel-types like Skarmory and Scizor that this team aims to handle for a Pinsir sweep. I really like Fire Blast Clefable because in my experience it's usually fairly to easy to predict, say, the Scizor switch-in and deal heavy damage. However, if the user of the team feels that Magneton is sufficient for handling Steel-types, Thunder Wave is a possibility, especially since it pairs well with Amoonguss's Stun Spore to spread paralysis. That said, the team already has a lot of status - Will-o-Wisp, Stun Spore, and Spore - so I think Fire Blast is the superior option.
In sum, Clefable:
- sets up Stealth Rock, a must for bulky offense
- handles Latios and other Dragons, which nothing else on the team can do
- handles Mega Sableye
- lures Scizor and Skarmory and removes/weakens them for Mega Pinsir