Heatran @ Leftovers
Ability: Flame Body
EVs: 248 HP / 8 SpA / 252 SpD
Calm Nature
- Magma Storm
- Payback
- Protect
- Stealth Rock
Latios is sometimes used as Heatran switch-in due to resisting all its common attacks, particularly when things like Rotom-Wash or Gliscor aren't present or are no longer up to the task. As long as it lands Magma Storm's 75% hit against Latios on the switch-in, this Heatran can use Protect to get some more residual damage, and then follow up with Payback on the next turn after tanking Latios' Surf. Even with minimum damage rolls on Magma Storm and Payback, this three-turn process is guaranteed to kill your standard Specs/Scarf Latios since the total damage will at least add up to 103%. Stealth Rock gives it another nice function as a hazard setter for the rest of the match as well, with Protect and Leftovers also allowing it to creep its health back up after taking 52-62% from Latios' Surf. The set's main drawback is that it won't work against CM/Roost variants, but those are generally much easier to check anyway.
The nice thing about the basic Magma Storm/Payback Heatran idea is that it's very customizable and can be changed around to fit your team. As long as it has at least 28 SpDef EVs it can stomach a Latios Specs Surf at full health, ensuring that the lure is successful off a connected Magma Storm on the switch-in. I went with this variant bc it can take Surf the best and will thus have the most use after Latios has been removed. Stealth Rock is entirely optional and could be replaced with Taunt, Earth Power, or Power Herb-backed Solar Beam depending on your needs. Dark Pulse can also make sense over Payback but only if you're investing in Special Attack and running a third attack to lean into the offensive aspects of Heatran.