>>56829354L
Lets talk about Serena deciding to become an idol in the anime, I don't think it suits her. An idol has to be more cheerful, playful, cheeky and a good liar. They also has to remain single because the very idea of them having romantic feelings for somebody would made their fans turn against them.
Serena is just too modest and passive to be idol, furthermore being an idol would make it harder for her to make a move on Ash. She was better off as a regular Coordinator rather than joining Lisia to form an idol group. Dawn has more suitable personality to be an idol than Serena