well if you're completely opposed to buying ninjas...there's really only 1 main that has a relatively high-level meta team of non-event ninjas, and that's water main. shark bomb + kurenai/gakido/sailor (2 of 3) + han.

contrary to their natures, the land of lightning treasure don't go as well with lightning main as they do with like, earth main or wind main. if u want a team from gnw treasure, it'll be kushimaru/jinpachi with lightning main, but the problem here is that you could get those rares on your 60th pull or your 960th one. not to mention this kushi meta is dying (or has already died idk) in some places.

i would really suggest you go for 1-2 event ninjas bc that would really help with making more useful/meta-relavent teams. jonin minato is a cheap and relatively good pos1 ninja to buy.

like i said, jonin minato is a pretty solid event ninja. he's pretty cheap now (~7k), and hits hard af. you can build an f2p team around him with like, wind main-iruka/SN-kurenai

kushina is also another good ninja, but i don't recall her being in events recently. most of her f2p teams include roshi, bee, water main (with poitai), sailor sakura or kurenai

if u want a good support ninja, 5kage madara is good. he's still new in the event cycle tho so he's quite expensive (~16-20k). you can do like, jonin minato-madara 5kage-water/fire-kurenai/sakura, or you could straight up do water main shark bomb + 2 debuff cleansers and madara 5kage in pos2

you're going to find people recommending angel konan probably. i didnt want to include her in this list because while she hits pretty * hard, she also works best with the likes of shark kisame. you can build an f2p pvp team around her, i just havent seen many of them.

yup this exactly. sorry if i wasnt clear.