In a recent PBP recruitment thread someone told me that, if you want to you can use the standard summoner with the unchained spell list. Since I can't find this rule anywhere (why google foo!) I decided to ask you guys if this is correct.
RainyDayNinja
RPG Superstar Season 9 Top 32, RPG Superstar 2014 Top 16, RPG Superstar 2013 Top 16
For PFS? No. You need to use the Unchained Summoner in its entirety for any new Summoners.