The title explains itself.
What I think they should explore/develop before the series ends:
1. Carrie and Darwin's relationship.
2. Development of more minor characters (such as Sussie, William, Alan, Carmen and Idaho).
3. Anais' social skills.
4. Nicole's maiden name and her side of the family.
It would also be great if Gumball and Darwin could be aged slightly, maybe to the age of 13. They have matured a lot since season 1 so I think it'd only make sense. Plus, Jacob and Terrell could stay longer if that were done. I also think it would nice if Logan Grove and Kwesi Boakye could return for one episode, voicing different characters of course.
What do you think?