I suspect that as a roaming he might appear in DM, GX, and 5Ds (maybe have lines with Yugi, Jaden/Yubel, and Yusei) but the actual unlock event he will only appear in 5Ds since he is a 5Ds antagonist and the event gate will be active at that point so you can duel him as whomever.
I mean, he's basically as canon to 5D's as Yugi and Jaden are. He technically has SLIGHTLY more plot relevance, but realistically he doesn't. (Given his only actual plot-affecting act was the events of Bonds Beyond Time, meaning Yugi/Jaden affected it just as much.) Either way he's a 5D's character (and will be treated as such), but going by how he affected the plot, Jaden is just as much of one.
He'll probably have dialogue specific for Antinomy, Aporia, and eventually Z-one. He'll probably have dialogue for both Yami and Regular Yugi, and he'll have dialogue for Jaden and Obviously Yusei, and quite possibly Pegasus
Diaage
Anoymous
