Has it ever been stated in any official sources just when the various characters were born? Or how old the Zoalords are?

I thought when the manga started show was 17, Mizuki 16 and Tetsuro and Agito were 18?

I think it said something like that, but I'm not entirely sure.

The anime gave ages in this data booklets but in the second volume the Lost Number pretending to be Mizuki went along with Sho's bluff and said 'yep, today I am seventeen' and that she was born in December. So it my faulty to think that just because the anime and manga are the same everyone else must be.