Lock if old
https://www.fantasyflightgames.com/en/news/2015/10/30/a-pilots-options/
The existence of two different decks creates a healthier metagame, further bolstering the current environment of creativity and amazing customization that X-Wing offers to its players. Toward that end, for the foreseeable future, players will also be able to choose which damage deck to use when building their squadron. The X-Wing tournament rules have been updated to reflect this change.
Please note that in order to showcase the new damage deck and provide spectators with a consistent experience, all competitors will use The Force Awakens damage deck at the 2015 X-Wing World Championship . One The Force Awakens damage deck will be provided for each competitor.
The Tournament Rules, which are now Version 3.2.3, say:
Edited by Danthrax
Players may choose to use either the original Core Set damage deck or The Force Awakens™ core set Damage deck.