Aladdin the Series: I'd make sure Aladdin's character was consistent. Seriously, he could be written perfectly one episode and then horrible and OOC the next. It was really aggrivating.
Ben 10: For the original series, tone down the Ben-Gwen feud as the show went on rather than sticking to the annoying status quo, which lessened both characters' likability. For Alien Force, I'd make it more consistent with the original series rather than retconning the heck out of everything. Oh, and I wouldn't kill of Grandpa Max so early.
Code Lyoko: Two words: Less. Filler.
Hey Arnold: I would make sure Arnold stays an interesting character rather than become a boring plot device. Oh, and I'd stop having every other episode be about Helga and her obsession with Arnold.
Kim Possible: I would tone down the "Kim can do anything" notion. I'm well aware that Kim needs to be a strong female heroine, but the show tends to go overkill with it, at some points decreasing her likeability.
Pokemon: This one's easy; I'd continue the show in the style it was going during the Kanto/Orange Island arcs, rather than the formulamatic style that it turned into from Johto and onward. And I'd get rid of Ash, Brock, Team Rocket, etc. once they've reached their peak, rather then drag them into the dirt of weak characterization like what's actually happened with them.
Teen Titans: I second the notion that I needed a better finale. I didn't hate Things Change myself, but it just didn't seem fit to be the last episode, especially since it was all about Beast Boy and not the whole team.
W.I.T.C.H: I'd have the first season stick closer to the comics in term of plot and characterization, particularly for characters like Cornelia and Cedric. As for the second season, I'd just have Nerissa, the show's best villain, be the final opponent, not Phobos and/or Cedric.
Ben 10: For the original series, tone down the Ben-Gwen feud as the show went on rather than sticking to the annoying status quo, which lessened both characters' likability. For Alien Force, I'd make it more consistent with the original series rather than retconning the heck out of everything. Oh, and I wouldn't kill of Grandpa Max so early.
Code Lyoko: Two words: Less. Filler.
Hey Arnold: I would make sure Arnold stays an interesting character rather than become a boring plot device. Oh, and I'd stop having every other episode be about Helga and her obsession with Arnold.
Kim Possible: I would tone down the "Kim can do anything" notion. I'm well aware that Kim needs to be a strong female heroine, but the show tends to go overkill with it, at some points decreasing her likeability.
Pokemon: This one's easy; I'd continue the show in the style it was going during the Kanto/Orange Island arcs, rather than the formulamatic style that it turned into from Johto and onward. And I'd get rid of Ash, Brock, Team Rocket, etc. once they've reached their peak, rather then drag them into the dirt of weak characterization like what's actually happened with them.
Teen Titans: I second the notion that I needed a better finale. I didn't hate Things Change myself, but it just didn't seem fit to be the last episode, especially since it was all about Beast Boy and not the whole team.
W.I.T.C.H: I'd have the first season stick closer to the comics in term of plot and characterization, particularly for characters like Cornelia and Cedric. As for the second season, I'd just have Nerissa, the show's best villain, be the final opponent, not Phobos and/or Cedric.