Do it whenever you feel like it. People who say dont use it, or that its risky etc etc - they’re all haters
I can’t really give you text book answers on when you can and cannot do it. It really just depends on your play style.
For example, many a time during ranking battles and tournaments, I will throw out a raging demon to win a round but not necessarily the match. Primarily because people don’t expect you to throw away your two bars, so they aren’t looking out for your setups.
The following round they will think that you have no meter and are therefore screwed. But bear in mind that Akuma has enough tools to keep playing even without meter. This works very well as a counter strategy when people try and rush you thinking that you can’t do anything cos of no bar.
Some characters however I would really prefer to have at least one stock against if they have enough energy to outlast a BnB combo.
Like I said though, its all about your own style and how you feel comfortable.
Actually, I think I might make a thread dedicated to using Akuma without super bar, or should I say playing him just to get the raging demon ready :devil: