So I kinda killed the only catchable Driftloon and now I need a new one. Idk if this counts as an unanswerable question, just pls help me out.
Drifloon regularly respawns every Friday after beating Team Galactic in the Valley Windworks. So just wait until the next Friday and a new one should be there. I recommend saving in front of the Drifloon so you can restart the game in case you knock it out.
Hope I helped!
If you knock out the Drifloon that spawns out front of Valley Windworks, it will respawn the next friday in the same place, at the same time. However, don't try to change your Nintendo Switch's clock to the next Friday, as this locks time-based events for 24 hours.
Source: https://game8.co/games/Pokemon-Brilliant-Diamond-Shining-Pearl/archives/348095
Hope this can help you!