If I had a quarter for every Christmas-themed American comedy that released this year about a family of four learning to understand each other after some magical hijinks (while the daughter worries over playing well in front of a professional sports scout so that she gets the chance to move away from her family), I'd have two quarters, which isn't much but it's weird that it happened twice.
Family Switch is a film clearly built to give its ensemble fun acting opportunities, with Jennifer Garner and Ed Helms being given excuses to loosen up more than expected, and Brady Noon and Emma Myers (arguably the movie's MVP) moving beyond mere imitation into more full-bodied performances as adults seeing through their kids' eyes. Unfortunately, the rest of the film saddles them with uninteresting situations that never take the body-switching aspect to more clever territory. Whatever mutual understanding that's learned by the end feels contrived, with the Christmas setting feeling especially tacked on—leaving these otherwise talented actors little to anchor their performances on.
As mentioned, Emma Myers is arguably the most impressive person in this cast—even with a boatload of eclectic cameos, which range from effective (Matthias Schweighöfer) to baffling (all of Weezer, for some reason). We don't get to learn much about Jennifer Garner's character (who later inhabits Myers' character's body), but the young actress manages to make do with what she's been given and be convincingly exasperated by the situation she finds herself in. The script doesn't give her very many directions to go, but either way Myers has made this into an acting exercise all her own.