Pulling Yachun up onto the tent requires that he does his Flurry at a target that is already on the tent. Yachun does his Flurry when his target a distance away from him. I think everyone knows this at this point in time.
What I think a lot of people don't realize is that you don't have to aggro Yachun to have aggro on him. He and his two bodyguards have linked aggro, and aggroing either one of them will aggro Yachun onto you as well. Thus, any class with a 16m range skill can just stand on the side ramp that leads to the top of the tent, hit one of his guards, back up a few steps and iframe. Boom, Yachun jumps to you.
Some things to note:
- If anyone hits Yachun with spells or a cat, the puller will instantly lose aggro on Yachun. If someone is doing this please don't hit Yachun.
- Try not to be too close to the top of the ramp. It is a bit tricky to find the sweet spot, but if you try this while too close to the top he will reset before he does his flurry.
- In a similar vein, you need to back up once you've aggroed them. If Yachun does not have enough room to fit between you and the edge of the ramp, he'll flurry under the ramp instead.
- I have done this on my Sum, WL, Sin, and Des successfully as well. Any class with a 16m range attack can do this (RIP KFM). I imagine BD and BM would have a pretty easy time doing this as well.
EDIT: After a eureka moment in which I realized I don't have to wear my faction uniform to be in SSP:
Heuk Bulmu Pull
His pull is much more straightforward, just stand at the the point of the V in the pattern at the top of the tent and hit him.