Downloading ROMs or ISOs for games you do not own is generally considered a violation of copyright law. Platforms like Reddit's Rom communities often discuss the risks of fines or legal action associated with these downloads.
If you just want a quick nostalgia hit, look into (has Galaxy 1 but not 2 — bafflingly) or Nintendo Switch Online + Expansion Pack (no Galaxy 2 yet). super mario galaxy 2 gdrive