A valid team will have:
- One Chosen with two Core vulnerabilities, one Significant, and one Minor;
- One Chosen with two Significant vulnerabilities, one Core, and one Minor;
- One Chosen with two Minor vulnerabilities, one Significant, and one Minor; and
- Each Vulnerability should be Core once, Significant once, and Minor once across all three Chosen.
So for example if you design custom Chosen A, B, and C with the following:
- Alice has Core Morality and Innocence, Significant Confidence, and Minor Dignity;
- Bonnie has Core Confidence, Significant Dignity and Morality, and Minor Innocence; and
- Clara has Core Dignity, Significant Innocence, and Minor Confidence and Morality.
That would be a valid team and you would run into Alice, Bonnie, or Clara on Day 1 (and the others during the first loop if they're the only three custom Chosen in your campaign).
If, on the other hand, your custom Chosen are:
- Alice has Core Morality and Innocence, Significant Confidence, and Minor Dignity;
- Donna has Core Confidence and Dignity, Significant Morality, and Minor Innocence;
- Elizabeth has Core Dignity, Significant Confidence and Innocence, and Minor Morality.
None of these characters can be on the same team (Even though Alice and Donna don't overlap any stats, they both have two Core Vulnerabilities. Alice and Elizabeth share Significant Confidence. Donna and Elizabeth share Core Dignity). In that case you might see Alice, Donna, or Elizabeth on Day 1 or you could see randomly generated Frida or Giselle and see one of your three customs at some point in the first loop, one in the second, and one in the third.
Hope that helps.