I finally got around to doing some serious research recently. There are private servers that let you download any fighter from day one, without having to buy anything. It took me about thirty minutes to set it up, and everything worked flawlessly on my phone.

The official app doesn't offer a free solution that covers all fighters simultaneously; the system is designed to slow down this process. A practical solution here is a private server. The mechanics of battles remain unchanged on such servers, which is important for serious build testing. For example, I suggest you find out more information here ​https://nulls-brawl.com/​​​