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.
Sonic Battle JUS Mugen V3 comes with a range of exciting features, including: Sonic Battle JUS Mugen V3
Dragon Ball Crossover (66 New Additions): A significant highlight of V3 is the addition of 66 Dragon Ball characters, allowing for epic "Sonic vs. Goku" matchups. It sounds like you're referring to a MUGEN
Refined AI: As seen in community showcases on YouTube, V3 updates often feature improved "AI Battles," making the computer-controlled opponents feel more like human players. Refined AI: As seen in community showcases on
But as the stun faded, the AI adapted. It teleported behind Shadow and countered with a Level 3 Super Move. A cinematic cut-in of Sonic’s intense face flashed on screen. The "Super Sonic Flash" filled the monitor with blinding white light and damage numbers.