Hi katakiri, nice to see that the DT Project gives to some good players the motivation to use stall.
From the moment you started talking about your weaknesses i couldn't help but think of SpD Celebi. A simple set of Psychic / Recover / Baton Pass / Perish Song and a 252 HP / 240 SpD / 16 Spe solves any CM Reuniclus, CM Latias, and CM Jirachi problem that you may be having. It can also prevent Toxicroak from setting up, unlike Amoonguss (after Sleep Clause is activated). I also really suggest that you use Toxic on Chansey instead of Heal Bell, which you don't really need to be honest. With Celebi on the team you have two Natural Cure users, one Magic Bouncer, and the other three Pokemon are immune to Toxic, so i think you will be fine.
Good luck and i hope you make it into HoF soon!
Part of the OU QC team, message
me for a check!