I am confused by which cards are actually event bonus cards. The current event

The eGacha listed 3 cards as alphas

Momoko Shirai (SR)
Koyuki Hiragi (R)
Mina Ayase (N)

And 3 Beta (I forgot their names)

There are now 3 new Alphas
Raika Seno (SR)
Kimi Kashima (R)
Setsuko Ooyuki (N)

Do these cards need to be in my Pero? Also what about the 2 cards you can trade medals for? Are those also "slayers"?

Anywho I am currently sitting at 1,146,249 Event SED if any one wants to invite me. I am having a bit of trouble taking on SEG by myself and my weak friends.

ID 1641092 Name: GamerBob