Swarms were present in all of the DS games but I remember them most in Diamond, Pearl and Platinum. Swarms gave you the opportunity to find rare Pokémon on other routes. You could find the Swarm Pokémon 40% of the time so this was very worth your time. These changed daily so you needed to act quickly to get that Pokémon in the area before it goes away. This was my favorite feature in any DS Pokémon game and this is what made those games memorable to me as well. What did you think about swarms? Do you think they should make a return in Sun and Moon or any future Pokémon game?
They were great for their time because it allowed you to fill the Pokédex further post-game, but I think Gen 4 style swarms are gone forever in favor of Horde battles. I think if they wanted to add something similar they'll just make it so certain Pokémon can only be caught in Hordes after (x) is completed, or something. Or they'll just do something like the Mirage Spots again which basically filled that same purpose.
I loved swarm Pokémon, I mainly followed up on them in BW and BW2 by checking the rolling screens in the route. I caught everything I could when the swarms were active since usually, it was Pokémon I missed out on getting before or Pokémon with a good typing. Not all the time but a good chunk of the swarm Pokémon were worth the hunt. I did have some issue running into them so it may have been me but it worked out ok in end after 5-10 minutes of hunting
Swarms were very handy for filling the dex. I remember checking the Message boards very often to see what swarm was going on that time.
