Short Answer: None.
Longer Answer: Seriously do not bother, those 1 HP sweepers are unreliable and very vulnerable.
- Vulnerable to priority (ExtremeSpeed, Aqua Jet, Bullet Punch etc)
- Vulnerable to weather conditions (Sandstorm, Hail)
- Vulnerable to status ailments (Poison, Burn, Confusion)
- Vulnerable to hazards (Stealth Rock, Spikes, Toxic Spikes)
Rattata @ Focus Sash
EVs: 252 Atk / 252 Spe
IVs: 0 HP, 0 Def, 0 SpD
-Filler (could be Pursuit)
This Rattata looks like it can net a kill on almost anything; however, it is also very prone to being setup fodder for a bigger threat. And trust me, I've seen this Rattata a lot and it is all too easy to counter-manoeuvre.
Magnemite @ Berry Juice
IVs: Null everything
- Fire Blast
This Magnemite's purpose is to take a hit, Toxic, then Berry Juice to replenish its health, then proceed to Recycle / Protect. Again, setup fodder, unreliable stuff, and yes, not exactly a 1 HP Sweeper but kinds of close.
I hope this helps