The Internet Archive’s software collection includes many user-uploaded ISOs and folder dumps of old games. Some are legitimate abandonware (e.g., DOS games from the 80s and early 90s). Others are much newer—like Madagascar 3 (2012) —and are clearly infringing.
Buy a used console copy or emulate the DS version. If you own a PC disc, use a no-CD patch from a reputable source (though even that requires trust).
However, because the IA has a vast library and limited staff, many copyrighted games stay online for months or years before removal. Some reappear under different names.