Well... do you mean f2p as cps ninjas in events? GNW Madara, Ss Konan, Zetsu/Suigetsu is nice.

Or do you mean non cps ninjas and ninjas which were for free in events? In that case... I would probably go with Shizuka, Gakido, summer Kurenai.

This team will serve you well once 6P Naruto gets BT .. just use Y chase on Naruto instead... I made a mistake

This team is one of old great teams... maybe you have these BTs and ninjas, and it still works... just not that well.

both teams are actually F2P ... Kakuzu EGF was in Fuku, GWN Madara was in Fuku, AC Kakuzu was in Fuku, Gaara is available completely for free, Taisho Konan was in Fireworks if Im correct... so pretty much for free...

Other than that as I made a bit calculation here :https://forum-narutoen.oasgames.com/page/show-post-49643-1.html

Convoy: 2 x 40 cps x 365 = 29,200 cps
Plunder: 50 cps x 365 = 18,250 cps
Tree (lvl10): 21 cps x 365 = 7,665 cps
being online: 10 cps x 365 = 3650 cps
Summon: 4 x 40 cps x 52 = 8,320 cps
Weekly miniclient (new): 100 cps x 52 = 5,200 cps
Full month attendance: 250 cps x 12 = 3,000 cps

F2P sum (without events): 75,285 cps

With events (and without Fuku deal) you can get 2 ninjas to 4* for free in a year... with Fuku, you can get almost any team in about a year... just set your goal, get those fragments for free when available and if not, go for power... simple as that...

You are not wrong... mostly... but high end teams are using all mains, depending on your (lets say) purpose of the team... Wind main can be extremely well working as well as water main... all depends on team and power on your main (eventually position power)... if your P4 can survive few rounds, all mains are relevant :)