First of all, I can see a lot of effort for this topic. Meaning you are one of those who are willing to learn more about the game, its overallness (if that is even a word LOLs). And that is a good thing, bro!

I actually can see alot of improvements that can be made, but I think overtime you will get to understand it on your own. First hand experience is the best teacher. I can see a good future ahead of you assuming ofc you continue to play like this [ hopefully :) ].

Since you ask for our opinions, yeah choji GNW is okay if and only if you already have him at 4 stars and bt-ed. He also scales hard when paired with Midnighblade, tho scarlet works just fine. I personally like scarlet's supporting abilities if i might add. At his 3 star state he is not that reliable. In early game I did use hashirama as a tank, Guy 4 stars as buff, scarlet and temari GNW - while cultivating my choji GNW. LOL pretty basic innocent team right? In early game I recomend to do not worry too much about getting highend ninjas, do not spend seals (tho i did spent 2-3 seals until i get Guy then saved after that) hehe let others get ahead of you. Do not rush for powers and focus on your initiative. I always tell this to my members, when you up ini, you lose potential power but overall you will do better. Anyways, only whales are capable of actually balancing stats cause they can get as many items as they please. If an f2p balance his stats, he will be left out big time.

Balance your Ninja fragments vs poweritems redeemables. For starters maybe just focus on atmost 2 or 3 at max OP ninjas when collecting. If you don't see them in any events, always claim poweritems. Actually I've experienced saing coupons 100% before and it is not as effective as i thought it would be. You may spend around 30-60 cps per week or even 100+ if that would mean you can get extra ninja fragments or even poweritems. Depends on your discretion ofc. Then when the right time comes, surprise them with what you collected xD

Again, I won't go into details on how to improve your set-up. But you will learn it over time. I believe in you bro. And btw, as an f2p, I can say you are investing in a good ninja [shikamaru chunin]. Make him full BT and probably 5 star and he'll do great in the future.

Here are some of the teams you c*e with chunin. These teams are some of my fav back then that I used frequently (kushina full sb). I just don't know if they are//will still be effective in the future. No one call tell hahaha

Anyways, this is just my opinion. I could be wrong. Enjoy the game and have fun!

Note: I understand this is a strategy section. Most of the players give their opinions for lineups and all, but in reality, most limit the infos they share ( I won't go into details, only legends know). It is good to see you are fully transparent of your ideas in creating this topic :))