There are two different types of RAM cart's. Your kinda getting the two mixed up I think.
1 - backup RAM cart. Used to store saved games in case you ran out of internal memory on the Saturn console.
2 - 1MB/4MB ram carts. Used to play SNK and Capcom fighting games. They used the extra RAM to cut down on the loading times in the game, and add more animations. KOF 95 came with its own special RAM cart that actually had all the backgrounds saved onto it. This helped it to load very fast. The other SNK games used any 1MB RAM cart, while the Capcom games usually used 4MB RAM cart. Although a few of the SNK games are also compatible with the 4MB RAM cart as well.