Turning red is just a metaphor for a girls period in a movie made for little kids. Parents would much rather talk to their kids about this kind of thing and not a have a tacky movie explain it to them when they are 8.
None of the characters were made to be very likable and are incredibly annoying. The characters are very unoriginal, and having them be stereotypical girls in the early 2000s, having tamagotchis and being into 4town which is clearly just supposed to be the Backstreet Boys.