It is unlikely that Sonic underground will get a continuation due to it being cancelled as a result of viewers dropping it.
Sonic Underground, I believe
well the freedom fighters are shown in Sonic the Hedgehog series and Sonic Underground series. both series are tv series.
Some people still see Sonic underground and some don't, but Sonic x is a brand new series that has better drawn skill of Sonic and his friends. Plus some new ones like Shadow The Hedgehog which is my all time favorite Sonic character.
AOSTH: no Sonic X: yes Sonic SATAM: no Sonic underground: no
There were two Sonic shows before Underground: The Adventures of Sonic the Hedgehog (AoStH) and Sonic the Hedgehog (SatAM). SatAM was similar in setting to Underground. There was also a film, entitled Sonic the Hedgehog The Movie (Sonic OVA).
Maybe they cancel the series
Sonic Underground is an animated TV series. And no, you cannot unlock episodes, or characters other than Sonic, from Sonic Underground in Super Smash Bros Brawl.
So far (As of 2009) the only series are: Adventures of Sonic the Hedgehog, Sonic Underground, Sonic the Hedgheog(Dubbed SAT: AM by fans), and Sonic X.
Not in the canon series. In Sonic Underground he is an orphan, but in the games he doesn't have a backstory
If you mean finish the story they have the next series coming out March 2013 check details on Retro Sonic >>>Sonic Underground To Be Continued...In Comic Form.
No,but who knows? They never finished the Series,it ended at Episode 40 I think.
Unfortuantly, Sonic Undergroud was canceled. It's been years...I don't think they'll start a new season, much less make a new gen sonic underground.