Stif, I don't see the need to go max HP on Dragonite without Roost. I would definitely like more Speed on Dragonite to outpace at least ScarfTar after a Dragon Dance (192 Spe EVs).
If you are having trouble with Rain, one simple fix can be Scarfing your Latios. That way, Latios can revenge dangerous Rain Sweepers, such as Starmie and Jolteon. It also comes in handy against Sun and HO teams. If you want solid coverage against Water-type, try specially defensive Gastrodon over Dragonite or SR Celebi over Heatran.
Celebi @ Leftovers | Natural Cure
Modest | 252 HP / 104 SpA / 128 SpD / 24 Spe
Giga Drain / Leaf Storm | Hidden Power [Fire] | Thunder Wave | Stealth Rock
Note: SpA EVs just enough to OHKO CB Scizor (after Rocks) and 2HKO 252 HP / 168 SDef Ferrothorn
I feel like your team has enough resistances to Psychic to play around OTR Reuniclus; you also have Mew and now Trick Scarf Latios to deal with Calm Mind Reuniclus. You could however make your Scizor a specially bulky SDer (248 HP / 40 Atk / 220 SpD, Adamant Nature) to better deal with not only Reuniclus, but Gengar, Choiced Latios, and Calm Mind Jirachi.