Hi got your request. From what I can see the biggest threat to your team is actually hazard stacking team. Right now you have no way to get rid of or delay the on set of hazards whether it may be Magic Bounce, Rapid Spin, or having Taunt users. Without any of these hazard damage is going to rack up quick against your Volt-Turn core (which is going to be switching constantly) and Dragonite. To alleviate these issues I am going to reccomend a Rapid Spinner over Rotom-W: Blaistoise.
Now I know Blastoise is a pretty unorthodox Poke to reccomend, but when I considered Starmie and Tentacruel in its place, I realized it opened up a very large weakness to Rock Polish Landorus and Mamoswine. Blastoise is bulky enough to comfortably check either threat and has access to Rapid Spin to make switching among your entire team easier. Unlike Starmie and Tentacruel it has access to Roar if you have the need to force out any threat. Your wish support from Jirachi will aid Blastoise into remaining healthy.
Trait: Rain Dish
EV's: 248 HP / 84 Defense / 176 SpD
If Blastoise doesn't work out you could always try Claydol>Landorus-T since it presents a similar set of resistances.