Sasori and Orochimaru: Sasori's abilities are puppetry, which is long ranged fighting. He is was the strongest Puppeteer while he was alive, being able to control up to a hundred puppets, and master with poisions, however his weak point is in the middle of his chest like a bullseye. Although he could move that chakra core center from puppet to puppet. Orochimaru master of summoning jutsu, curse sealing technique and his powers include his ability to change bodies and also the eight headed snake jutsu.
Pain and Konan: Nagato master of the Rinningan (although not as well as the Sage of 6 Paths), six paths of pain; Asura, Naraka, Human, Deva, Animal, and Pretta (projectile, ressurection, soul stealing and mind reading, gravitation, multiple summons, absorption of chakra), and Chibaku tensei. Konan's abilities are her paper based origami jutsu, with her greatests technique being her 10 minute long explosion.
Pain and Konan are the stronger pair. One Animal path can overwhelm Orochimaru's snakes and also the two shinobi in general, Naraka path can ressurect any fallen path given the event Orochimaru and Sasori take them down (unless Naraka path is destroyed), Pretta path can absorb any chakra pased ninjutsu (although neither Sasori or Orochimaru have been seen using any techniques like that although Sasori's chakra strings could be absorbed preventing the use of puppet maniuplation and also not allow him to maniplate Sandaime Kazekage's metal sand), Pain's gravity can destroy/repell multiple opponents and weapons leaving Sasori's puppet techniques useless. Really I can't remember the last time I've seen Orochimaru fight except for Hiruzen and Sasuke. Pain I believe can deal with the two himself however Konan would provide valuable back up.