Given I'm not coming back after tonight, I may as well throw even more of my reputation to the wolves!
Perhaps the greatest post I have made on /vp/ was pic related, a year ago yesterday, last Thanksgiving evening.
I carefully watched the number of the latest post on the board, with the thread in question open and my post prepared, until the 9999 was reached. Once I saw those perfect zeroes at the end of my post, I eagerly awaited for it to be noticed like a six-year-old in bed on Christmas Eve. Then the Bronzong "witnessed" post appeared, and the rest is history. I admit I made some posts of my own as the thread neared page 10 a small number of times to revive it, which I do feel a little bad about, but it was worth keeping the thread alive for a full week.
I have every reason to believe that it got the most responses I ever got on a non-OP post on /vp/ or on the site in general. Unfortunately, it's not the most replies I've ever gotten on this site; that distinction goes to a thread I made with an image of that one Beauty in the Battle Maison with the text, "Reminder: This is canon." If you know what I'm talking about, I'm sure you can imagine how that played out. It still didn't last as long as the thread I derailed with my fabulous 0000 did, though!
I made this screencap myself; I'm aware there was another. This get occurred shortly before the domain change from 4channel to 4chan occurred, and this actually erased all of the (You)s I had, hence why there are only a few, the ones I'd already captured, on the image. Given you believe that I didn't just edit the (You) text in, if you doubt that it was I who made the get, you're welcome to search for the filename on Nyafuu.
Anyway, those quads pale in comparison to these sexts!
https://play.pokemonshowdown.com/battle-gen7anythinggoes-1015162441 