I found an app called PS2 Controller Remapper on YouTube and it showed that it changed the default mapping to a different one by generating a cheat code.

I tested it at PCSX2 Nightly v1.7.5449 on DMC1 for both US/EU releases which I mapped Triangle to Melee, Jump to Cross, and Shoot to Circle. At first, I generated PNACH code but after seeing a program made by the same dev (PS2 Patch Engine) that can permanently patch the codes to the ISO itself, it became possible.

This patch allows you to play the game with the JPN/HDC Type A control scheme BUT Melee textures will still say Circle so you might get confused. Also Confirm and Cancel will be Circle and X, like the common JPN PS games.

Link (xdelta GUI + the Patch Files): https://www.mediafire.com/file/vwuxxasnoquq1ss

This thread might be useless since HDC already exist.

i really would like to have an emulator category , but its not up to me to decide that. emulator at the moment is banned for both dmc3 and dmc1