I see that you're currently running a water main. I wish I could recommend you the team that I'm currently using, but you're missing 2 of the components.

But I'll still go ahead and spill the beans. You can choose to hear me out, or don't. It's your choice and no harm to come either way.

I'm currently running Mu (3 stars), Akatsuki Orochimaru, Water Main and GNW Sakura, in that movement order. As you can see, it's not going to cost you a bomb. Very achievable even as a F2P. The whole gimmick came about because I thought it'd be funny to have two self-reviving characters in my team.

Generally, I'll try to immobilise as many of my opponents as I can with Mu and Orochimaru. Poison Tai is used for damage as well as to bait out Mirror Return. I picked GNW Sakura because if her slugs die, it'll generate more chakra for me to do more AoE with.