Spoiler:
Voices that probably are not returning:
Doc Harris as the narrator - Said he wasn't back when asked in an email.
Dale Wilson as Cell, Kami, and King Yemma - Said he doesn't remember recording for this dub when asked in an email.
Terry Klassen as Krillin, Guldo, Cell Jr., Roshi, and Grandpa Gohan - According to NitroEX, Brian Drummond confirmed at a con that he isn't back; he's transitioned entirely into directing.
Paul Dobson as Zarbon - Kirbopher has allegedly claimed to have talked to the "New" voice of Zarbon.
David Kaye as Recoome - He works out of LA now, so we can be pretty certain he's not back.
Robert O. Smith as Grand Elder Guru - Passed away in 2010. It is possible he was auditioned and did all his voicework for it in 2010 before he died, since the character isn't in a lot of episodes, but it's highly unlikely, especially since the last work he's known to have done was back in 2005/2006.
Jason Gray-Stanford as Raditz - He hasn't really done much voicework since the '90s, so he's unlikely to be back.
Pauline Newstone as Freeza - Recast in favour of Lee Tockar.
Ian Corlett, Peter Kelamis, and Kirby Morrow as Goku - Morrow was re-auditioned, but ultimately rejected. The other two were allegedly not auditioned. Richard Ian Cox was cast in this role instead.
Matt Smith as Tien Shinhan - Rejected in favour of the Calgary actor who played the role in the Blue Water dubs, Brendan Hunter.
Voices that are returning:
Scott McNeil as Piccolo, Jeice, Caroni, Dr. Brief - Confirmed at a panel.
Michael Dobson as Nappa - Acknowledged on Twitter.
Brian Drummond as Vegeta - Confirmed in an interview.
Brendan Hunter as Tien Shinhan (Blue Water) - Confirmed at a panel.
Known new voices:
Richard Ian Cox as Goku - Confirmed by Scott McNeil(Via a user in this thread), Kirbopher, and I believe also KaiserNeko
Lee Tockar as Freeza - Confirmed on Twitter.
Cole Howard as #17 - He mentioned it in a Reddit post. Account now deleted.
Trevor Devall - Unknown role. Confirmed in an interview, and briefly touched on in an episode of his podcast.
James Beach - Unknown role in episode 21. Likely an unnamed Namekian. Confirmed in a forum post where he asked for a copy of the episode to use in his demo reel.
Voices that may be returning: (Excluding actors we've heard nothing about)
Ted Cole as Yamcha - According to NitroEX, Brian Drummond said he may be returning. We know he was recast as #17 in favour of Cole Howard, though. Assuming he was re-auditioned as Yamcha, he was likely also re-auditioned as Korin aswell.
Saffron Henderson as Gohan - She made a Tweet that many believe refers to getting to play Gohan again for Kai after having initially dropped the role due to having to move to California. She was "Temporarily replaced", as she put it, for the rest of Z's run, and as I recall didn't return to Canada until after the Westwood Z dub was over, so it would make sense if she was returning. Ultimately, we can't be 100% sure at this time, but I would say it's likely what she was hinting at.
Don Brown as King Kai, Emperor Pilaf, Burter, Moori, Hercule/Mr. Satan, Shenron, and Roshi - He still works, and Brian Drummond said on Twitter that he's worked with him somewhat recently, so the jury is still out on this. I would say he was at the very least re-auditioned for the role.
Scott McNeil as #16, and farmer in field - He has talked about playing basically all the same characters as he did in Z, including mentioning Boo, Old Kai, South Kai, and Dabura, but a handful of his old roles haven't been mentioned, and we're also unsure if he's gained any new roles this time around. If Alec Willows isn't reprising Oolong, there is precedent for McNeil playing that character in Willows' absence, after all... Whether this all just slipped his mind, or if he's been recast in some of his old roles is not known, though he can be quite forthcoming about this stuff at cons when asked. (Similar case for any characters not mentioned above played by actors I've mentioned)
Other misc. info:
According to Kirbopher and others, the idea of doing both a cut and an uncut version of this dub was discussed. We have no way of knowing which way this went, however a cut version does exist.
The edited video master for this dub's production was licensed by Funimation, though with their episode titles used instead of Ocean's. This video master is what aired on NickToons USA. It's possible this edited video master was only produced in standard-definition. Ocean are credited for their work in the closing credits to the NickToons edit.
The edited video master gives us some small insights into one or two things about this dub; chiefly, the tournaments will be referred to with a direct romanisation, "Tenkaichi Budoukai", instead of the localised "World Martial Arts Tournament" title Funimation's dubs, and productions that follow their naming conventions, have used in the past.
Allegedly, the scripts are new, original scripts done by Ocean. I forget who talked about this, probably Kirbopher.
The romanised name of the Tenkaichi Budoukai goes along with the more-accurate approach this dub seems to be taking in other areas, with Freeza's recasting away from Pauline Newstone, Goku's recasting away from Kirby Morrow(It's not online at this time, but Kirby Morrow said in the famous Voiceprint podcast episode 26, "They let me re-audition to see if I could kid him up a little bit, make him a lot more childlike [...]"), and the fact Namek will be pronounced closer to how it's pronounced in the Japanese version.
Karl Willems was the primary ADR director of this dub, according to Brian Drummond via SX10.
At least one other ADR director was involved in some capacity, as allegedly at least one person connected to this dub who'd talked to Kirbopher knew it to be directed by someone else.
One of the first people to be cast in this dub was allegedly Scott McNeil. James Beach allegedly heard some of the music for this dub, so he likely recorded much later in the production.
Because Maggie Blue O'Hara was not in Vancouver at the time this dub was recorded, and I believe the same as true of Lalainia Lindbjerg, it's probably safe to assume we're getting a new Bulma.
The exact number of Vancouver-based actors vs Calgary-based actors is not known, but rumours go around that the bulk is from Vancouver.
The last few seconds of the opening theme song are available via the online editing supervisor's demo reel. This video also notes "2 seasons", which gels with the CRTC listing of Kai(Page 2) as "DRAGONBALL KAI (I)(#1-50)" and "DRAGONBALL KAI (II)(#51-98)", which suggests it was packaged and officially considered as two "Seasons" of about 50 episodes each. This snippet also gels with something David Steele said about a 30-second snippet of a song called "Dragonball Kai" on his website: "I did that spot in 2009 and unfortunately don't have any info on it as I was just hired to sing, I can't even remember if it was a demo or went final?" The voice in the editing demo reel version doesn't sound like his, and the instrumentation sounds entirely different. It's possible the lyrics are also entirely different. So, while the 2009 demo which has been going around online has been known as "The opening to Ocean Kai", it is likely nothing more than a scratch track, if that.
Sean Schemmel has seen a small amount of this dub, which had a replacement score and an altered SFX track, likely because of Funimation's acquisition of Ocean's edited video master.
Last news we heard on this is that Marni Shulman of Wow TV in Canada is still working on acquiring it. It all seems to be going smoothly, so all we can really do is sit tight and wait for an update from her.
I personally would be rather surprised if Dave 'Squatch' Ward isn't back as Ox-King.
Doc Harris as the narrator - Said he wasn't back when asked in an email.
Dale Wilson as Cell, Kami, and King Yemma - Said he doesn't remember recording for this dub when asked in an email.
Terry Klassen as Krillin, Guldo, Cell Jr., Roshi, and Grandpa Gohan - According to NitroEX, Brian Drummond confirmed at a con that he isn't back; he's transitioned entirely into directing.
Paul Dobson as Zarbon - Kirbopher has allegedly claimed to have talked to the "New" voice of Zarbon.
David Kaye as Recoome - He works out of LA now, so we can be pretty certain he's not back.
Robert O. Smith as Grand Elder Guru - Passed away in 2010. It is possible he was auditioned and did all his voicework for it in 2010 before he died, since the character isn't in a lot of episodes, but it's highly unlikely, especially since the last work he's known to have done was back in 2005/2006.
Jason Gray-Stanford as Raditz - He hasn't really done much voicework since the '90s, so he's unlikely to be back.
Pauline Newstone as Freeza - Recast in favour of Lee Tockar.
Ian Corlett, Peter Kelamis, and Kirby Morrow as Goku - Morrow was re-auditioned, but ultimately rejected. The other two were allegedly not auditioned. Richard Ian Cox was cast in this role instead.
Matt Smith as Tien Shinhan - Rejected in favour of the Calgary actor who played the role in the Blue Water dubs, Brendan Hunter.
Voices that are returning:
Scott McNeil as Piccolo, Jeice, Caroni, Dr. Brief - Confirmed at a panel.
Michael Dobson as Nappa - Acknowledged on Twitter.
Brian Drummond as Vegeta - Confirmed in an interview.
Brendan Hunter as Tien Shinhan (Blue Water) - Confirmed at a panel.
Known new voices:
Richard Ian Cox as Goku - Confirmed by Scott McNeil(Via a user in this thread), Kirbopher, and I believe also KaiserNeko
Lee Tockar as Freeza - Confirmed on Twitter.
Cole Howard as #17 - He mentioned it in a Reddit post. Account now deleted.
Trevor Devall - Unknown role. Confirmed in an interview, and briefly touched on in an episode of his podcast.
James Beach - Unknown role in episode 21. Likely an unnamed Namekian. Confirmed in a forum post where he asked for a copy of the episode to use in his demo reel.
Voices that may be returning: (Excluding actors we've heard nothing about)
Ted Cole as Yamcha - According to NitroEX, Brian Drummond said he may be returning. We know he was recast as #17 in favour of Cole Howard, though. Assuming he was re-auditioned as Yamcha, he was likely also re-auditioned as Korin aswell.
Saffron Henderson as Gohan - She made a Tweet that many believe refers to getting to play Gohan again for Kai after having initially dropped the role due to having to move to California. She was "Temporarily replaced", as she put it, for the rest of Z's run, and as I recall didn't return to Canada until after the Westwood Z dub was over, so it would make sense if she was returning. Ultimately, we can't be 100% sure at this time, but I would say it's likely what she was hinting at.
Don Brown as King Kai, Emperor Pilaf, Burter, Moori, Hercule/Mr. Satan, Shenron, and Roshi - He still works, and Brian Drummond said on Twitter that he's worked with him somewhat recently, so the jury is still out on this. I would say he was at the very least re-auditioned for the role.
Scott McNeil as #16, and farmer in field - He has talked about playing basically all the same characters as he did in Z, including mentioning Boo, Old Kai, South Kai, and Dabura, but a handful of his old roles haven't been mentioned, and we're also unsure if he's gained any new roles this time around. If Alec Willows isn't reprising Oolong, there is precedent for McNeil playing that character in Willows' absence, after all... Whether this all just slipped his mind, or if he's been recast in some of his old roles is not known, though he can be quite forthcoming about this stuff at cons when asked. (Similar case for any characters not mentioned above played by actors I've mentioned)
Other misc. info:
According to Kirbopher and others, the idea of doing both a cut and an uncut version of this dub was discussed. We have no way of knowing which way this went, however a cut version does exist.
The edited video master for this dub's production was licensed by Funimation, though with their episode titles used instead of Ocean's. This video master is what aired on NickToons USA. It's possible this edited video master was only produced in standard-definition. Ocean are credited for their work in the closing credits to the NickToons edit.
The edited video master gives us some small insights into one or two things about this dub; chiefly, the tournaments will be referred to with a direct romanisation, "Tenkaichi Budoukai", instead of the localised "World Martial Arts Tournament" title Funimation's dubs, and productions that follow their naming conventions, have used in the past.
Allegedly, the scripts are new, original scripts done by Ocean. I forget who talked about this, probably Kirbopher.
The romanised name of the Tenkaichi Budoukai goes along with the more-accurate approach this dub seems to be taking in other areas, with Freeza's recasting away from Pauline Newstone, Goku's recasting away from Kirby Morrow(It's not online at this time, but Kirby Morrow said in the famous Voiceprint podcast episode 26, "They let me re-audition to see if I could kid him up a little bit, make him a lot more childlike [...]"), and the fact Namek will be pronounced closer to how it's pronounced in the Japanese version.
Karl Willems was the primary ADR director of this dub, according to Brian Drummond via SX10.
At least one other ADR director was involved in some capacity, as allegedly at least one person connected to this dub who'd talked to Kirbopher knew it to be directed by someone else.
One of the first people to be cast in this dub was allegedly Scott McNeil. James Beach allegedly heard some of the music for this dub, so he likely recorded much later in the production.
Because Maggie Blue O'Hara was not in Vancouver at the time this dub was recorded, and I believe the same as true of Lalainia Lindbjerg, it's probably safe to assume we're getting a new Bulma.
The exact number of Vancouver-based actors vs Calgary-based actors is not known, but rumours go around that the bulk is from Vancouver.
The last few seconds of the opening theme song are available via the online editing supervisor's demo reel. This video also notes "2 seasons", which gels with the CRTC listing of Kai(Page 2) as "DRAGONBALL KAI (I)(#1-50)" and "DRAGONBALL KAI (II)(#51-98)", which suggests it was packaged and officially considered as two "Seasons" of about 50 episodes each. This snippet also gels with something David Steele said about a 30-second snippet of a song called "Dragonball Kai" on his website: "I did that spot in 2009 and unfortunately don't have any info on it as I was just hired to sing, I can't even remember if it was a demo or went final?" The voice in the editing demo reel version doesn't sound like his, and the instrumentation sounds entirely different. It's possible the lyrics are also entirely different. So, while the 2009 demo which has been going around online has been known as "The opening to Ocean Kai", it is likely nothing more than a scratch track, if that.
Sean Schemmel has seen a small amount of this dub, which had a replacement score and an altered SFX track, likely because of Funimation's acquisition of Ocean's edited video master.
Last news we heard on this is that Marni Shulman of Wow TV in Canada is still working on acquiring it. It all seems to be going smoothly, so all we can really do is sit tight and wait for an update from her.
I personally would be rather surprised if Dave 'Squatch' Ward isn't back as Ox-King.