Is there any information about how catch rates work in these games? It seems pretty likely that they are very different from the capture mechanics in previous gens but I haven't been able to find any reliable information about how it works.
There was testing by, I think, dragonfree that seemed to point that there's a catch rate penalty in place if you are lower level than the pokemon you are trying to capture, with this penalty lifted after beating the game. They used special balls and the catch rates seemed to line up otherwise, though.
But beyond that I don't think anything has been determined. If I ever start the game over, though, I am incredibly tempted to just buy 100 great balls and start chucking balls to see what's going on, because it's been very unusual to see so many people (even those outside of enthusiast forums) notice issues with catching things that shouldn't cause trouble at all and the great ball in particular has been a point of contention .
...For standard captures, anyway. For
raids, we have some hard numbers
Standard pokemon, Solo or as Host: 100%
Standard pokemon, Assist: Species catch rate (not flat %, the actual catch rate)
Gigantamax pokemon, Solo: 100%
Gigantamax pokemon, Host: Catch rate 20
Gigantamax pokemon, Assist: Catch rate 3 (NOT A TYPO)
Standard event pokemon (ie: if you run into a normal snorlax right now), Solo, Host or Assist: Species catch rate
Gigantamax event pokemon (ie: if you run into a g-max drednaw right now), Solo or as Host: Catch rate 20
Gigantamax event pokemon, Assist: Catch Rate 3