Example: Normal Espeon vs. DW Espeon
Espeon(N) uses Toxic on Espeon(DW). I know the Magic bounce will reflect back on Espeon(N) so when Espeon(N) gets poisoned will Synchronize come into effect and make Espeon(DW) poisoned too?
Yes, the DW Espeon will be poisoned. Magic Bounce only reflects a status once a turn.