About Raids

If you do raid in a large group then it doesn't matter.

lvl 30 should be good enough, has been a good threshold

if you want to translate that into CP, then a lvl 30 machamp would be like 2400 cp i supose, i think just for mention one example

Don't look at cp, look at the level of the pokemon, it's moveset and its type advantage over the raid pokemon.

In level 4 raids, it all depends on how many people are participating.

In level 3 raids, if you are more than one, it shouldn't be a problem. If you are soloing you need L30 attackers that are type effective with great movesets.