This needs more attention. I wasted a good, fun 4 hours doing this with Mekkah in Heart Gold.
Most of our 6 battles were centered around Geodude. Geodude's fantastic resistances and immunities in Normal, Flying, and Electric made it an incredibly useful pivot. It helped that all of the Pokemon that it was 4x weak to were either too weak or had a terrible movepool that hardly justified using them as they had a bad offensive typing. It also helped that we agreed to not use starters so we couldn't use Totodile or.... Chikorita to beat Geodude. Despite Geodude being extremely strong, we still found ways around it. The battles were also surprisingly long, but that started to change when our Pokemon got more powerful attacks. Currently the record is 4-2, me having the 4 wins of course.
I suggest anyone here who is interested in the 30 minute challenge to try it! #orangeislands is an excellent place to search for matches as there are quite a few other interested people there.