A late game rain abusing Dnite is almost unstoppable if you use him correctly. If you're legitimately not having much success with it, you probably just suck. :/
I admit it, I do suck T.T. But rain abuser Dragonite is really easy to deal with. I don't even bother with it while teambuilding, and usually end up with a way to deal with it anyways.
-all other forms of weather, especially hail, shut it down cold
-Subtect Gliscor can outstall it
-all other forms of Dragonite win against it
-No one outhaxes Jirachi, EVA! screw your confusion, I'magonna parahax u to death
-Latios meteors KO regardless of Multi Scale (unless you're gay and run a scarf)
-Reuniclus says a big fuck you and sets up on it
-Haxorus rapes Dragonite's wife, children, and entire extended family, then proceeds to rape Dragonite itself.
-Starmie rocks it hard with Ice Beam
-Landorus rapes it
-Terrakion molests it as well
-Salamence, absolutely sodomizes Dragonite, as the jealous younger brother, he kidnaps Dragonite's wife and kids. Rapes Dragonite's wife in his face. Then proceeds to rape Dragonite through the @hole, while forcing Dragonite to engage in intercourse with his kids, leaving Dragonite to kill itself in shame.
-Latias walls and sets up on it, or Dragon Pulse twice if you're paranoid of confusion hax
-Unless you get confusion haxed, Gastrodon can toxic stall it
-Hydreigon, man it seems every member of the dragon family engages in violent sexual activity against Dragonite (except Druddigon, the unattractive disabled outcast of the dragon family who couldn't get laid by an overweight Vibrava)
-Mamoswine lets out a mighty roar, and drops massive icicles onto Dragonite, then drops more icicles on Dragonite's dead body