Hey dude. I'm a lvl 69 who started as a water main. I swapped to a lightning main to help do more damage. The truth is water main is used solely for healing which means you would usually need to have a rare ninja which you usually get acess too at lvl 70 through GNW treasures. (You get a few more types of treasures at 60 and 65 but it's recommended to wait till 70 for the better ninjas. because if you get a "bad" draw its still gonna be a great ninja war Neji or something as opposed to the normal variants you get. Late game gameplay = keeping thag one strong rare ninja alive to carry you. Which is why earth and water scale better into the late game.

Since you have GNW Sakura. As for lightning main you will eventually replace Hinata with kimimaro (given free) but he gets ridiculously strong at 3* which should be what you want him at. Your Sasuke also needs to get his stars to 3 at least for new skills.

As for ninjas in shop, I learnt this the other day but the best think we can do is buy the cheap fragments. E.g. Hinata, Kabuto, rock lee to help build them to 5* asap because you will unlock fragment refining which will basically give you a better shop Because you can trade the excess for rarw ninja fragments such as iruka. (My Hinata is only 3* now because I only learnt this two days ago but I did my research and this is the most "value" you will get.)

for water main a good team to use until you get some better ninja is water main, gnw sakura, hinata, and sasuke (3 star)

gnw sakura - water main - X

X - sasuke - hinata

X - X - X

talent: 2,2,3,2,3

summon: white snake, bull, or small katsuyu (doesn't matter which one)

as you can tell, if your using this team, your main wouldn't be the main healer (she actually doesn't need to heal at all if you use gnw sakura, but it does help some if her standard is the healing jutsu)

this team has a good combo too

farther into the game you c*e this team:

water main - fuguki - X

X - sasuke - gnw hinata

X - X -X

talents: 3,2,4,3,1

summon:white snake

you can still use regular hinata, but the extra standard attacks from gnw hinata will definitely help you.

I'm a level 75 water main and I used to use the first team. it was a great team as long as you know how to use it

I'm currently using the second team and it's working wonders for me :)

for ninja you should be working on getting....

many people in my server are using the sailor sakura, roshi, fuguki team. I personally don't know how well this team is, but getting these ninja won't hurt. Also ninja like Mei Terumi, Chojuro, Edo Tnesei Haku and Zabuza would be good choices. You can get most of those ninja in the kage treasurre, edo tensei treasures, and jinjurikii 2 treasures. sailor sakura can be bought in treasure of the sage.

I hope this helped you at least a bit :)