Fun Fact(s) about every Dokkan Battle Anniversary. (Share yours in the comments!)
Apologies in advance as my memory may be fuzzy on some of the stuff
Year 1 - to this day still the only Anniversary where you either pulled (one of) the new unit (s) or your account was just forever cursed and bad. Super Gogeta was so insanely broken at the time that people REROLLED THEIR DAY ONE PROGRESS just so get Gogeta with the available free stones. Not a single unit since came close
Year 2 - this is more of a sad fact than fun, but the side TURs for both of the SSJ4 headliners are still among the oldest units to not receive an EZA yet. This is actually hilarious because both main DFEs already EZAd, they're in range for a Super EZA within the next year, and even the Year 4 LRs EZAd in the meantime, with the 7th scheduled in just under 3 weeks
Year 3 - bit of a persobal opinion but I think it was the only Anniversary that had absolutely nothing to do with the headliners theme-wise. The celebration as a whole was basically Namek coded from start to finish and yet the part 1 units were....fusions? We will never know for sure but Bandai may or may have not changed plans at the last moment because you could argue the Goku and Freeza DFEs we got for that year's WWC had artwork worthy of LRs despite being TURs. Very strange all around
Year 4 - Shortly before the details were officially revealed, there was a post in this very sub with the LR rarity artwork for both of the headliners, some calling it fake and others just dismissing it as fan made. Well, it wasn't just the unit art that leaked ahead of time. We actually knew about the kits for SSJ4 Goku and Vegeta before they released and Akatsuki significantly buffed their passives. Initially they were only going to have like 80% ATK & DEF start of turn boost and that's it, no notable mechanics or other boosts to speak of. They'd be completely trash on arrival
Year 5 - since this Anniversary heavily featured DBS Fusions, we got an expansion to the Broly movie story event, which added like 5 new stages with medals to Dokkan awaken each of the 4 F2P TURs. On top of Goku and Vegeta getting their exclusive stickers from missions, the SSJ Broly and Golden Freeza are still among the oldest story event units dropped around Anniversary period to not have been given EZAs, even despite the fact that Year 9 featured the movie in part 1
Year 6 - an all around monumental celebration because it has arguably the best f2p units ever (aside from the tutorial reward Saiyan Saga team), so much so you could take them to the challenge event available back then and find success because of their utility, between Roshi/Tien sealing, Krillin/18 stacking, and LR Roshi dodging and stunning. Plus this is where we got our first category leader AND gold coin LR EZAs for the first time ever. The Dokkan subreddit went apeshit when UI Goku EZA was revealed
Year 7 - arguably the most massive meta shift in game's history. Yes, we had the move from basic type leaders to rainbow leaders to class+type leaders to category leaders, but the introduction of 200% leader skills and the difficulty of first two Red Zone events combined caused pretty much majority of units to become nonviable overnight. We'll see what the bosses at the end of year 10 look like since we now have 250/220% leaders but this Anniversary provably will remain the most significant power creep
Year 8 - some could say this is the most controversial Anniversary because Omatsu was promising that this was going to be the celebration that features characters never before seen during any of the previous 7 annis. As it turned out, he basically lied and "poorly worded" his statement, because technically SSJ3 Goku, SSJ2 Vegeta and base GT Goku haven't been headliners prior to the 8th. Also this was the first Anniversary where the part 2 units became carnivals instead of the usual gold coin LRs, making them that much less available due to Carnival banner scheduling
Year 9 - due to the whole "version sync" situation being handled extremely poorly by Akatsuki, Global kind of had an insane year in terms of delays/pacing/uncertainty in regards to when we'd actually start getting content alongside JP. This likely made the developers sort of "apologise" (or let's be real - bait people into spending all their stones before Beast), and part 1 of the Anniversary had a never before seen banner format with 7 steps where you could get two featured units guaranteed for 250+ stones. That format was used ONLY for part 1, and part 2 went back to the usual 3+1 multis with GLB tickets. It has now been 7 months and we have yet to see this format be reused for...well ANYTHING, really. It did not return for WWC, it did not return for New Years, and it did not return for Year 10 part 1. Will we see it again? Who kbows at this point
Year 10 - okay so not exactly a fun fact but I think throughout the entire history of the game this was the first major celebration where we had no idea what to expect. Of course there was the warm-up coin design which people typically don't pay attention to in hindsight, but there were all kinds of predictions between fusions, Goku and Vegeta with branch transformations, Heroes vs villains, etc. And of course it's the first Anniversary to have a total of SIX new summonable units, 3 per part across parts 1 and 2