You wont really get great results because most Fire Main teams/ at least decent ones contain multiple specific ninja that are usually behind pay walls.

Ideally you want to be Water Main, in all honesty.
You have Han/Roshi, Sailor Sakura & you also have Mabui/Mei/Tenten.

Realistically you're looking at using the same line ups you use with Water Main but with Fire Main, he also can utilize Mabui/Tenten/Mei lineups, as well as Han/Roshi lineups, obviously results will be different.
Any other line ups that can be made just wont be as effective as what you can do right now with Water Main, we'd be only creating line ups for you that are worse than what you're capable of utilizing.

oh, okay. Thank you for taking the time to respond.

I agree, I'd say LM and Water Main are most F2P friendly although LM is falling behind a lot in the current meta except for Shisui teams or Madara blitz

But to respond on your original question , yeah Fire Main would need the more rare ninjas