Kabuto is amazing for Survival and Strong Approaching (that's my only use for him as a Fire Main). Then choose what you think you will use. You can collect Hinata ones as well, very useful for basic f2p line ups.

The rest (at the top of my head) are pretty much pokedex fillers. ;P

You c*ways go for Itatchi in Arena or even go for Tobi (I think he is in arena not sure off the top of my head)

who is better suited to fire main?

From Group shop, redeem Medium refines (i assume you're f2p?, so those would be valuable; otherwise Kisame or wait for konan)

Edit: Karin is farmable from Elite instances and Survival, so she is a waste of group points. She is good, just... not from group shop. Those refines stack up over time. This post was last edited by Mitrandir at 2017-3-31 18:45

Stock up on as many points from all the shops as possible. It may take months, maybe even more, but one day we will get to the point where you will be able to buy some of the best ninjas in game via this points in star system.

As for what you should buy before stacking up on these :
Group shop - Only Medium refines. If you are just starting you may get anko 2 star (if she is 2 star ninja)
Arena - Nothing from here is really necessary. I'd recommend to keep these for yourself.
Ranking - You may want to get hinata, and low refine runes. Other than that keep.
Survival trial - You may want kabuto nothing else really.

Summon - You are free to do with these whatever you want, they are not used in star system later on :)
This post was last edited by TakafumiNaito at 2017-3-31 19:41

Group shop : Med refine (the best choice atm)
Arena shop : I have no idea
Ranking shop : Hinata (u need her for exam)
Trial shop : Kabuto (he is decent)

karin is farmable from survival trial? how?
i am f2p. so when does konan appear? This post was last edited by Battojutsu at 2017-3-31 23:16

so i shud gather lots of runes, get kabuto, upgrade hinata.
after that i should just keep stocking them?

Karin will some time drop as a reward from treasure boxes. As for konan she will be available in one of the shops some time next month but they have not released what shop she will be in yet

Also stack up on med and low refine runes until a wish rebate is up it will help you get a little stronger depending on how many runes you have to put into it.

wow. thts surely helps a lot. ty

You can farm Karin from Elite Instances.

She can drop as a reward from clearing survival trial.