I think this belongs to strategy section but since we are here. As a fellow F2P, here is what I use in Group Summon but it c*so be used in 9tails.

You can replace Passive1-4 to passive1-1 (if you die in Summon MS but if not you can sthick***(they keep on censoring the word stck) to this for l10 rounds buff).

You can replace standard 3-4 if Mys doesn't hit you that hard.

I ddon't have WB yet, i think he can be used if you have his 70% life bt (for scarlet).

Chases of lee and yamato is not needed, maybe passive 2(+2) of lee can help.

if you have Naruto sxy you can place him for lee but change your scarlet's standard to "2" for sure chase

Allways buff your scarlet as much as you can. hehe i don't have naruto sxy yet as well.

Lee and iruka can be replaced, but yamato i think better stay, and scarlet as the mvp

Now I know I am not an expert but i think this is a decent one hehe. Other opinions should be considered as well.

Hope this helps. Have fun!