Ok so today I was playing some player matches and ALL my opponents teams had phoenix. I stop playing this game for like 2 weeks and no I come back and every person has phoenix now? Well anyway I went to training mode to discover a technique of chipping Phoenix to death but I discovered something totally different.
I Kara command grab (H) after C. L, C. M (sorry I dont know how to add those buttons icons)
anyway after crouching L input couching M but RIGHT after that input QCF H for the command grab, instead of getting the crouching M animation the running animation of the command grab should come out instead. Giving you a free combo killing phoenix. And Yes it works well with advancing guard (i think it works the best with advancing guard and the best thing is that Phoenix use use that advancing guard like crazy!).
Well anyway, I hope this helps fighting that whore. I havent tried it on all the characters but I believe it should still work the same.
Edit: Also works with or without corners.