Board Thread:Questions and Answers/@comment-27168366-20160109214941/@comment-679780-20160808031122

Erik.wallace.395 wrote: Out of ALL of the MANY stories of how Sonic met Tails, I only found 3 different stories: The beginning of Sonic 2, episode 18 of Sonic X, & episode 16 of AOSTH. I don't know which one is real. The beginning of Sonic 2 is regarded as canon. Though the others can be regarded as canon for their own series which are seperate from the games.

But to be less confusing, yeah, Sonic 2 manuals stories are regarded as canon.