It sounds like you're referring to a MUGEN fighting game build titled "Sonic Battle JUS Mugen V3" — likely a fan-made crossover featuring characters from Sonic the Hedgehog and Jump Ultimate Stars (JUS) style gameplay or sprites.
Balancing Adjustments: The update standardized HP across all fighters and implemented specific buffs (e.g., Sonic Black, Amy, Espio) and nerfs (e.g., Hyper Sonic) to ensure fairer gameplay. Roster Highlights Sonic Battle JUS Mugen V3
New Stages & Music: Over 140 stages (including 20 HD versions) accompanied by remixed tracks from the Sonic franchise. It sounds like you're referring to a MUGEN
Performance Tiers: The game is released in two versions: an OpenGL version for high-quality graphics and a DirectX version optimized for low-end PCs and laptops. Character Roster Highlights Performance Tiers: The game is released in two
Sonic Black: A buffed version with custom English voice lines, teleportation, and Chaos Control.
Expanded Roster: Beyond just Sonic and Shadow, V3 often incorporates obscure characters like Emerl or Chaos, all redesigned in the JUS sprite style.
The “V3” designation indicates this is the third major version of this specific fan project, typically featuring a larger roster, balanced movesets, and refined stages compared to earlier versions.