Doubles battlers, I will present to you a pokemon that you will probably not usually consider for support, that does it exceptionally well:
Breloom is a fantastic support mon that has great use against rain, sand and hail teams! Unfortunately it is rather useless against sun as most offenders can 2hko it at worst even after toxic recovery.
Breloom's doubles geared movepool and typing is simply fantastic, I'll list a few of the more awesome moves.
It's important resistances are to surf, discharge, earthquake and rock slide and it can survive most non STAB blizzards and heat waves! I Highly
Recommend toxic heal as the status immunity is priceless and the recovery allows you to deal better with occasional ice beams, flamethrowers and sludge bombs.
Here is a sample set:
Breloom @ Toxic Orb/Leftovers
Trait: Poison Heal
252 HP / 8 Spd / 248+ SpDef
-Drain Punch / Helping Hand
-Seed Bomb / Helping Hand
Drain punch and protect keep it healthy and this Breloom is difficult to ohko from full hp with special attacks, seed bomb allows you to nuke specific threats on weather teams and spore works great with fake out support to neuter threats and especially trick room! Helping hand is a move that fits Breloom well and allows it to facilitate wall breaking for its partner. Leech seed is an option over seed bomb or spore in order to maximise healing and harassment. Leftovers is an option over toxic orb if you have something to toxic you earlier in the match.
Breloom is particularly good at countering disquake combinations and walling sand and sun teams in general, usually I find it best to pair it with a powerful sweeper that can put pressure on opponents immediately in order for breloom to give it the right helping hand and spore support.
For now, I haven't put too much effort into ev'ing it but it might be useful to EV it to take certain hits such as a non item boosted blizzard from 252+ Abomasnow or a draco meteor from Kingdra and pump enough ev's into attack to score critical ko's or 2hkos such as against Gastrodon, Excadrill, Politoed and Abomasnow
edit: 252/36/220+ Breloom gives you a good chance of ohkoing even the most defensive Gastrodon (without rindo) whilst surviving the aforementioned high powered moves (252+ Aboma blizzard + hail damage and LO 252+ Kingdra meteor). Unfortunately Breloom can never ohko Excadrill with drain punch but has a very good chance to ohko non-chople Tyranitar running max HP.