I have a copy of the DS "version" which seems to be completely different, should a category be created for it?

I think if it is a completely different game, rather than the same game but on a different console, then it probably should have its own page. However, I'm not an expert on this stuff, so I'm not sure what typically happens in cases like that. The games share a name, so I wouldn't be against adding it if you still want to speedrun it.