I think this show isn't that bad. The only concern is the fantasy violence, but it's fantasy and even my 3-yr-old sister isn't frightened by it. And I love it! It doesn't have much crude humor. SpongeBob SquarePants has a lot more crude humor than this! It's also a great show that kinda teaches friendship. So I think this is appropriate for all ages.
I love zatch bell! The whole "every episode has violence" is a lie! Zatch fights to stop violence because of a momodo girl named Kolulu. the last thing she wanted to do was fight. And in the episode that I think was called "Zatch Vs. Kio!?" the only battle is "kick the can" and the entire episode is about friendship.
Some episodes will really make you cry. I cried when Kalulu and Danny died. And Rops. My sister wanted to see that episode with him! :( I also cried in the episode about Sherry. How terrible for that to happen to Koko! Another bad thing is there was a song called "Groping Breasts" and the lyrics were "Breasts, breasts, and boobies!" (NOTE: In the dub, it was changed to "hey, hey, let's dance all day")
This show has lots of violence but it it is a good show that teaches about friendship. Commonsense wasn't exactly accurate about the tobacco thing though, because in one episode someone put a cigarette in their mouth. I love this show a lot!