[@VeyrinDay]

To answer your question, you can mention the limitations in either the power section as further elaboration under the specific power or under the weaknesses, whichever you prefer. 

[hider=My Two Cents Regarding Powers]
However, with the very nature of superhero RPs and the various power levels of the threats, I find that the upper ceiling and specifics of your character's powers are best left vague so you can adjust them as you need. That way, your "broken" combos can still be used later on but be held back early on due to story elements like the character's inexperience, hesitation, and whatever else. The charging time you suggested is a good implementation of inexperience that you can reduce or get rid of later on, plus you can do a training story arc too.
[/hider]

Note: I'm not the GM but I've been in 3 of [@Omega Man]'s JL RPs before and I believe that's how he rolls his non-stat based RPs.