"The team is complete."
Translation:Die Mannschaft ist komplett.
yes. and also same goes for these: "-heit", "-keit", "-tät", "-ung".
I think they're completely interchangalbe, although in more formal context, I would use vollständig. Komplett sounds more casual to me. I can't justify why, though. Edit: Oh, but: When talking about groups of people, you most often would say 'vollzählig'.
My last sentence keeps bothering me. vollzählig is used to say a group is complete, they're all here now, everyone has arrived. In duo's example 'komplett' means every position in the team is manned now and before, there was for example a goal keeper missing so they couldn't attend matches. When showing up at the match, which is now possible since they're vollständig, and the coach is still missing, they are not complete yet either, but here it would be vollzählig – not each of them is there yet. komplett and vollzählig are often interchanged in a colloquial or casual situation, so it might be hard to distinguish the difference sometimes. I hope the above explanation might help with that.