Nothing, and I repeat nothing, beats everything 1v1 without previous setup. Flinches, freezes, choice scarves, crits, etc. can and will cause problems in unexpected ways as you go, which is the danger of relying on lots of 1 for 1 exchanges. I suspect, if you have a team built to maximize such exchanges, that you already are using a Focus Sash poke, but if you aren't, Destiny Bond Focus Sash Gengar is able to trade 1 for 1 a very high fraction of the time. However, note that the Destiny Bond user is KOed before the victim of the Destiny Bond, so Gengar functions best as a lead, and his Destiny Bond won't save you in a third poke on third poke situation.