As much as I don't like to admit it (seeing as how I really like Mario and how much I hate Link's overratedness) it's true. Many of the points I was going to make have already been stated. Besides Mario and Link being the most liked by Nintendo fans and them being the two most recognized Nintendo mascots (I somewhat think Pikachu might be a little more popular than Link though). Shigeru Miyamoto (a Nintendo producer) was also in charge of making them both if I remember correctly. Also Mario and Zelda games seem to be getting the highest game ratings out of all Nintendo game series (Mario spinoff games being an exception since people seem to enjoy hating on).