Out of the box, you only have access to a handful of Legends (currently, the free rotation offers 6-8 characters per week). To have the full experience—the ability to counter-pick, play random, or master every weapon combo—you need to unlock them all.
Please note that using third-party tools to unlock characters may void your game's warranty and could potentially harm your computer. Use at your own risk. Brawlhalla Unlock All Characters Download Pc
If you don't want to spend money, you can unlock characters individually using How to earn: Out of the box, you only have access