Anyone hoards up rare candies? For what purposes?

Me too.. I am now having about 400+ rare candies. Patiently waiting for my first ex-raid pass to dump about 200-300 of them. I used my rare candies on the legendaries if I am low on item space, cause legendaries are much more justifiable since others you can easily get by catching/walking, but legendaries only through RAID and buddy need a massive of 20km to get a single candies. Anyway, do not have any plan of powering up any legendaries yet, just use it if too much.

Well it's 66 candies to go from level 20 to level 30, then 64 more to level 35 and then 118 to level 40.
In total that's 248 to go from level 20 to level 40, so in reality 245 rare candy (as you get 3 when you catch it).
Are you really likely to get three Mewtwo that you will want to take to level 40 before you get another 245 rare candies?
I took my first Mewtwo with rubbish IV to level 30 and have converted enough rare candy to take another to level 35. The rest I've put into other legendaries. There is no way I could use 700 bag space for rare candies!

Is that the total amount of rare candies that you have got, or did you convert some already?

I use rare candies for legendaries only and have taken Raikou and Moltres to Level 38 and 38,5. I have a little over 300 left, which means 245 for Mewtwo and no idea where to put the remaining candies (maybe the last level ups for the two legis). I might put some into Gardevoir as soon as I get a good IV candidate. Other than that I will save up for Groudon.

Waitin for mewtwo...

I'd say especially

Groudon, Kyogre, Rayquaza, Mewtwo, Raikou/Zapdos and maybe Moltres/Entei are worth spending rare candy on.

So if you already have a great electric Pokemon (Raikou/Zapdos) and are still waiting for Mewtwo, it is not completely unreasonable to stock up rare candy.

I would then immediately transfer ~200 candy on your first Groudon / Kyogre / Rayquaza / Mewtwo and wait a while before powering up the first "good" one (to me "good" = 93%IV with 15 att)

I've always been keeping 66, while mostly using them on Raikou, Zapdos, Ttar, and a small number on Blissey. Now, I'm saving more for Metagross and Salamence.

I've powered up Raikou and Mewtwo, and still have over 500 candies left. I'm not sure what I'm saving them for. None of the other legendaries to date really seem to warrant them (though I'm close on Entei and would do Articuno 'cause it's my team bird). Maybe it's more I don't want to spend my STARDUST than I don't want to spend my Rare Candy. In any event, Gen 3 legendaries actually look, well, legendary, so perhaps I'm hoarding it for them (though I admit it's taking up a lot more bag space than I'd like).

I was till I realized how silly it was to keep all that "rare" candy. Being able to keep 700 isn't rare so I started using them and only keep about 100 - 150 at a time. I haven't been using all of them to power up because of the stardust issue so I have been putting the extras into Dratinis for evolution have about 5 lvl 20 dragonites just for collection purposes hoping one day for trading.

You can convert Rare Candy to candy for any legendary (that you already have) to save bag space without spending any stardust (as you do not have to power up said legendary immediately).

I have 1200 rare candys and can’t get a ex raid pass to of load them?

Hoarding because I have nothing to use them on. 600 in bag and it's starting to hurt. Mewtwo, Groudon, Kyogre would help, none of the legendaries I have are worth transferring any more on. Next best target is Blissey in case I wanted to make a third maxed one, but I don't want to spend the stardust that requires.

same problem here. Still waiting for mewtwo or other stronger gen 3 pokemon like Salamence.

I've 500 rare candies. I've:
max out 2x Dragonite;
max out 3x Blissey (138 chansey candies left);
3x Tyranitar to level 36 (420 larvitar candies left);
1x Zapdos to level 38;
1x Raikou to level 30 (66 raikou candies left).

and now I don't know what to do.
What are you guys having as your walking buddy?

I've taken 1 each of all the legendaries (except lugia and suicune) to level 30-32. I've dumped ~360 into Mewtwo (in order to get 2 to lv31 and 1 to Max). I'll start hoarding again but if bag space gets tight I'll start the long road to maxing out the legendaries that are already powered.

Someone made a compelling point to me. None of the Legendaries are really all THAT much better than some other mon you can already get at level 30 (now 35!) which is effectively "free". So really legendaries are a luxury and if you are willing to put rare candies and stardust into a luxury then why not max it out for the absolute best performance? (in other words it's not worth 75k dust and 66 candies for marginal performance gains)

I'm in no rush to get there, I have other priorities first, but I really can't argue with that. So eventually I'll start powering up my Raikou and Moltres.

I have been putting my rear candy into all the legendaries going along, so that I more or less have the possibility to power up at least one to lev 40. So far I have only powered up a couple to lev 30 (Articuno and Lugia). Suicune is the only one I have avoided to feed with rear candy to date. I am constantly filling my bag with balls, max potions (approx 250) and max revives (>400), feeding regular berries to gym and deleting unnecessary items to keep under max limit. I do not keep any rear candy as this would have prevented me to accumulate the other items. I will of course feed Mewtwo should I get an invitation to an ExRaid. I am walking Blissey as it is very difficult to get hold of them in the wild and I also do not want to use rear candy for it.

I had well over 750 before I decided it was time to spend. After a few months I decided to max a Mewtwo. The first day gen 3 came out I found a 91% 15 atk and HP slakoth. Maxed it by the time the day was over (regret) currently sitting on around 250 candies. Mudkip is hella rare for me. blaziken will be the most useful attacker. Almost have the candy to evolve a Torchic - but no where near enough to power one. Still waiting on a good IV candidate. Depends how long it will take. Ill either drop it on a blaziken or wait for the next batch.

I thought about hoarding Rare Candies, but when I hit 120, and saw how underwhelming most of the Legendaries have been in the current Meta (they aren't BAD, but they aren't game breaking) I stopped hoarding them. I'm keeping about 60 in reserve for any potential Mewtwo that I might get (which ain't gonna happen. Nope, not gonna happen - not until they change the EX Raid format or it's summer. Too bloody cold to raid outside now), but other than that I'm spending other Rare Candies on Pokémon which have 5km buddies and aren't easy to catch in the Wild, like the Dragonite and Tyranitar groups. I might hit up the Slaking group (if I catch or hatch a decent one) or the Ralts group (got a couple nice ones, but none I'm seriously interested in powering up. Got a Level 35, but only Attack of 7, so... meh). The Dragonite group is rare where I live and work, and I've never seen a member of the Tyranitar group in the Wild, ever, so they're the ones I put most of my Rare Candies into.

Or on the few decent Legendary's that I've caught - I've got a Raikou that I've powered up to level 33 with Rare Candies. I might power up a few of my Ho-Oh's (finally broke my streak last night and didn't catch it. Sadness - it was a 2199, the highest I've had a chance to catch so far) if they prove to be useful.

Here is where I've used varying amounts of rare candies, and still have 375, and 1.8 million dust:
Maxed a Mewtwo - PC/FB that I use to attack most gyms
brought another Mewtwo up to level 30 as PC/SB which gets no use.
Two Raikou (100%) to level 39, and another (98%) to level 31. I use the twins all the time in Suicune and Ho-Oh raids, and attacking gyms
One Zapdos (98%) to level 31, hardly ever use.
One Entei (96%) to level 38, use a good bit attacking gyms.
One Articuno (98%) to level 39, waiting for dragons.
One Ho-Oh (100%) to level 33 so far. ES/BB for Ho-Oh now, will swap to SB for Groudon.
Transferred some to Togetic (414 total candies)
Transferred some to Porygon (482 total candies)
Transferred some to Tangela (419 total candies)

I am currently hoarding rare candy to dump into Mewtwo. Although I caught him yesterday, I still haven't put any rare candy into Mewtwo only because I was trying to figure out how good Mewtwo is...My Mewtwo is 84% IVs so I wasn't sure if he was the one I wanted to power up. Course I don't have another EX invite....

But I think I would put some rare candy if I ever got a 100% Larvitar and/or Dratini and give my nephews my level 40 TTars and Dragonites if the trading ever happens.