dunno if this counts but lol
Metang @ Focus Sash
Trait: Clear Body
Serious Nature <------ note, this can be anything really lol
Sceptile @ Life Orb
EVs: 252 SAtk / 4 SDef / 252 Spd
- Giga Drain
- Hidden Power [Rock]
- Focus Blast
Okay so, the first thing you do is send in dMetang when one of them is sent out, if your lucky and THE MIGHTY METANG effect takes place and they time out, excellent! but it doesnt really matter whether it lives or not. Once Metang has died you go to sceptile and OHKO both of them with hidden power rock and giga drain, respectively.
Sadly, i really doubt that anything can switch into both of these without a problem, i mean barely anything can switch into moltres alone even if it misses, same for tops, the power of a +2 stone edge or even aqua jet is insane :/. Another factor is that a good player will try as hard as they can to make sure neither of these pokemon can come in except after a KO.
my way of beating the core, personally is just to stop either of them from switching in, and if one of them does get in safely, to predict around it, or if worse comes to worse, sac something and bring in a pokemon that can outspeed and KO both, in my case sceptile. This is how most offensive teams deal with threats and cores like this, chances are nothing can switch into such a powerful core, but if you have a pokemon like sceptile, you can probably sacrifice a pokemon you dont need and start up your own sweep =).
Edit: just checked and i dont think theres any one viable pokemon that can accomplish it ;-;.