I personally like to save my meter for pretty much just two things:
1) Breakers. Sure, its 2 bars, but being able to save life and give myself some momentum is really helpful.
2) EX Forceballs. I don't really use them all that much, but when the opponent starts to turtle hardcore and doesn't have a teleport, a charged EX Forceball combined with following it with regular dashes or getting in front of it with an Elbow Dash makes for insane high-low mixups (I guess medium-low in MK format?
)
X-Rays can be useful, and make great punishes for some things that would normally be unpunishable with its armor, but with Reptile's easy BnB dealing 3
9% and a more advanced one dealing 45%, compared to a raw X-Ray of 33%, generally speaking in my opinion it'd be more efficient use of meter to either simply not use it or use one or two bars for a few extra percent, as opposed to three bars for what could very well be less.
Then again, the practicality of pressing 2 (or 3) buttons to do that much damage may outweigh the meter use, especially in an intense environment like a tournament.
In a 2v2, though, Reptile's assist is godlike.
Fully charged EX Forceball that you can abuse with dashes, teleports, and dashing attacks (like Kabal's run or even various slides)?
Simply amazing.