I'm not sure if there'll be a consistent term of it for a while. How I'll incorporate the colon into the title would probably depend mostly on how much I actually end up liking the show, but I also pronounce "Xros Wars" "Csros Wars" for all time, since I don't believe that particular Anime deserves to be called anything less silly than that.
But let's assume a neutral environment...
"Digimon Adventure 20" has been suggested somewhere but I feel that's kind of an accident waiting to happen for anyone typing fast as it could turn into "02" very fast and get confusing.
And in the end the colon is right there on the keyboard it's just kinda small and looks silly when you want to use an actual colon after it. But it's easy enough to set it in bold+cursive for example: Adventure :
... and already it jumps out more and looks less like a boring everyday colon, and that might just be clear enough.
If you want to be more fancy, there are some variations of the colon like ⦂, ꞉, ∶ and ː.
...Most don't really look like much but personally I've really fallen in love with the first variation (used in Z-notation according to wikipedia), especially combined with bold: Digimon Adventure⦂
...It still clearly resembles a sort of colon but no one would think that it's used normally, it also catches the eye and won't be easily overlooked. So I guess that would be my choice for now.
