Board Thread:Questions and Answers/@comment-31435758-20170304072556/@comment-679780-20170304073607

Short answer no.

Long answer, Cosmo is a licenced original character to TMS Entertainment who is indeed owned by Sega but specifically for the  Sonic X series and Sega have no interest in importing characters from other spin-off series from the franchise into the main games.

If they would, it be likely we'd have Sally and maybe other Freedom Fighters long before Cosmo would be considered.