I did it! Hard challenge!

[Sephiroth]

Aerith does not only have one LIMIT like you say. And using them or defeating enemies with her like I did are worth what you get (faster LIMITs, seal enemies when you need them), the priorities are different depending on what the challenge is like, like the How to get MP is important when fighting Ruby with ES only. Then there is still Yuffie, very well used for Emerald, and depending on the challenge several other methods. Some people also use Inns. There is a great variety of what a challenge can look like and how you keep your HP up or to help your stat otherwise.

The thread starter for example did not use items. I don't know if he used armor and accessory. They are also items in a way but they can be very useful in case you decide to use them.