For me :
- Azure Moon for all paralogue , Crest relic, Sacred weapon and their battaillons.
- Silver Snow for paired ending (28 character, 14 men (Byleth count) and 14 women). Can make 14 paired ending.
As the title says, create your own student at Garreg Mach Monastery. Include their name, house, rank (commoner or noble), proficiencies and a description of their backstory and what they're like both as a person and as a student.