As I say pretty much every time this thread comes up, you almost have to go with unknowns if animorphs is ever made again, because you know what happens if you don't? Who's the right age? Miley Cyrus for Rachel and the Jonas brothers for Jake, Tobias, and Ax. Actually, given her portayal as Jane in Twilight (not that I saw it... cough) Dakota Fanning might be able to pull of Rachel, but she too will be too old soon.