With my latest info, there's like 3 layers: Lead, which is like a sleeper (e.g. Jynx) or a powerful sleep absorber (e.g. Tauros); choices out of Slowbro, Chansey, Exeggutor, Snorlax and Zapdos; using Mew and Mewtwo. My viabily ranking thread still says Chansey and Slowbro are S because I went on a streak of like 17/18-0 with using Lead + Exeggutor, Chansey, Slowbro, Mew, Mewtwo, but since I got wonderful countered by the Zapdos + Snorlax core vs that team, I realised that middle layer shifts around. A few more tournaments will probably have to be hosted until we figure out the high level metagame exactly.
Edit: Also, the transform stalemate to me seems to be solved by banning either transform, or a combination with it, if it occurs too regularly, or the need for some mechanical clause (possibly expansion of endless battle) to end battles that get into this and similar stalemate situations.