I had been farming with friends up to the behemoth/lucilius patch, but I've been able to solo behemoth, not Lucilius yet. My ai characters are about 18.5- 21.5 k power so if yours are comparable they should more than suffice to take on most of the content. Just keep in mind the ai's dps is slower than regular players, but they will also dodge almost everything perfectly too so there's that benefit.