Gen 8
Lanturn @ Leftovers
Ability: Volt Absorb
EVs: 252 Def / 4 HP / 252 SpD
Calm Nature
IVs: 0 Atk
- Thunder Wave
- Confuse Ray
- Scald
- Volt Switch
Lanturn still struggles to be somewhat viable, but it has potential for it. Don't expect it to stand against any of the current high tier meta, but do expect it to leave off some of its very annoying impact for those unsuspecting victims.
Now, you're running Para-Fusion along with a potential Scald burn, which should be clear what your job here is. This little fishy has both some speed and bulk to it, so keep that in mind as you start off with T-Wave. Once you get that off, you will most likely have a free Confusion as well, and with a little luck gain a free move.
This means your opponent will either be switching out, or struggling their way through to kill (be mindful, those determined can likely take you out in 2-3 hits). The setups are in your favor here, so whether you choose to stall a bit, Scald-Burn a likely switch, or simply Volt Switch out of there is your choice.
Lanturn has very little healing options, so you should be careful when it's worth sacking it and when you can predict the all-common Regileki or Fishious Rend to get some HP back. (Though you won't live either of those, but you may get Regi to switch.)
Calm Nature gives you a little more SpD, and Leftovers are pretty much Lanturn's only way of healing. Its Abilities I suggest basing over the current meta rather than anything else, as it tends to be ever-changing depending on GameFreak's next Mega Rayquaza of the generation. It's likely you'll be switching the two if you find the other fitting you better.
Edit: I meant Confuse Ray instead of Confusion, typed wrong. Thanks for pointing out!