Sorry if I sound condescending, but I read your post and I was worried that someone might think you're serious.
Jumpluff is a terrible Garchomp counter. First of all, you are weak to two of its most common moves (Fire Blast and Stone Edge). Secondly, relying on "prediction" should only be a last resort in any situation, since your opponent is "predicting" just as much as you are. Thirdly, what is Jumpluff actually doing to counter Garchomp? Oh no you encored me and now I have to switch out after you did no damage to me and exposed what your "counter" is so I can easily 2HKO it next time and now I can only switch in pretty much any OU pokemon to wall your Jumpluff completely and make you start backpedalling.
But other than that, Jumpluff is a good counter to Garchomp.
Also, Cloyster really isn't a counter to Garchomp either although it would make a good revenge killer. It doesn't resist ANY of Garchomp's moves, is weak to Stealth Rock, and generally has better things to do anyways. That's like saying that Gengar makes a good Starmie counter.
Heh, uhh I don't think that the sarcasm at the beginning of your post is going to make your post sound any more intelligent so don't even try that. Geez...
First off, notice how I put the word counter in quotation marks? That's supposed to note that it's not an actual counter, because the word itself is extremely vague.
Second, Garchomp hardly ever carries Stone Edge unless it's Choiced, and most don't carry Fire Blast unless they're the Chain Chomp variation. I'm saying that this is good for the SD variation. If it's Choiced, I take care of it like I do with any Choice user.
Why exactly should relying on prediction be a last resort at all? You're supposed to be using prediction the entire match, so if anything, it should be a first resort. With Garchomp especially, there's no 100% counter which has been stated a million billion times in this thread, so every one of Garchomp's "counters" SHOULD have to rely on prediction, because Garchomp has a way of taking out every one of them if they predict wrong. Even the ones that come really close like Cresselia can be taken out by Garchomp.
What is Jumpluff doing to counter Garchomp? Well, there's the Encoring, but also let's see...Sleep Powder? How about Subseeding? After you Encore him, Jumpluff can also U-Turn out while Garchomp is switching to give you the advantage.
Heh, why exactly would it matter if Jumpluff gets walled? It's not like it's an offensively-based pokemon anyway. I won't exactly be "back-pedalling" if your switch-in gets statused or hit with Leech Seed.
I'm not sure about this, but are you saying that a "counter" always has to be able to deal a huge amount of damage to the HP of the opponent they're countering? If so, that doesn't make sense, because then how exactly does Blissey counter anything?
Geez, I never even said that Jumpluff was a good "counter" to Garchomp, I just said that's what I personally use to stop him. This thread is opinion, I don't really see the need to say that something's terrible at it's job when you haven't used it for this purpose and I obviously have. Notice how many times I said "for me" in my original post.
Also, about your Cloyster paragraph, first off, why'd you mention Gengar being a good counter to Starmie? That has nothing to do with Cloyster being a "counter" to Garchomp. Cloyster has good defense, Gengar has terrible defense, I don't understand the relation.
You also said that Cloyster has better things to do than stopping Gengar. Like what? If you're implying that it should be a spiker, then it's pretty much completely outclassed there by the other spikers. Stopping Garchomp would actually make it useful, so why not? It doesn't really matter if it doesn't resist any of Garchomp's moves. Blissey doesn't resist a great majority of the special attackers' moves, but it still stops them anyway...