Generally, anything that banned in A1, A2, or A3 is banned in HSFA.
Autoblock (because it’s fucking stupid)
Shin Akuma type stuff
Those weird A3 modes (mazi, l-ism, whatever they’re called)
…and HSFA CE-ism. (pink-ism)
General consensus is CE is stupid broken good. Mainly because of the HUGE damage and HUGE dizzy potential. You can kill someone with 4 button press combo with some characters.
http://youtube.com/watch?v=qntJH6NquO4 for some examples.
But, to be honest, I don’t think anyone really knows if CE should be banned. It IS stupid fucking good, but at the same time, so is a lot of other stuff. CE also has weaknesses. People really haven’t played this game enough to flesh out tiers or anything fully.