Pong predates the Atari VCS by several years. Actually I think the first cartridge (ROM) based systems were designed primarily to be able to recreate Pong and Tank style games, but turned out to be much more capable than that.
There seems to be several Pong clones, but none that I have experience of. The problem with this particular game is that usually you want analog paddle controllers for that fast, immediate action. It means the game should support analog joysticks in the game port for a reasonable accurate experience.
For various reasons I won't give you download links, but a bit of searching for pong dos will give you roughly two million hits. Many may be irrelevant, but at least you should be able to find 20 or 50 games to download and try.