Here's half of the headcanons because I'm falling asleep as in writing the rest here
~Soulsilver~
Oldest: Amber A Soul
Youngest: Garnet G Soul
(Silver took Lyra's last name to disassociate himself from Giovanni)
1. Amber is an exact copy of her father
2. Garnet is like neither of her parents
3. Amber loves battles
4. Garnet prefers contests
5. Garnet lives in Sinnoh
6. Garnet models
7. Amber is a tad bit jealous that her parents let Garnet go off on her own
8. Amber is suuuuper gay
9. Amber's team consists of: Furret, Pidgeot, Ninetales, Lanturn, Hitmonchan, and Nidoqueen, with Furret as her partner
10. Garnet has four Pokémon- Pachirisu (shiny), Skorupi, Croagunk, and Skuntank, with Pachirisu as her partner
11. Garnet loves poison type Pokémon thanks to her father's Crobat and Gengar
12. Amber has no idea what she wants to do with her life
13. Garnet's father does not approve of her career choice, but is supportive anyway
14. Both children have their father's eyes
15. Garnet doesn't know how to ride a bike
15b. Amber makes fun of her for it
~Original~
Oldest: Violet L Oak
(I can't find/come up with a last name for Red, so we're just gonna go with Oak)
1. Fluent in sign language
2. Amber's rival
3. Likes to have a plan
4. Has already planned the next twenty years of her life
5. Always at gyms before Amber
6. Battles by the book
7. Violet's team consists of: Venusaur, Raichu, Nidoking, Dewgong, Hitmonlee, and Dodrio, with Venusaur as her partner
8. Caught Nidoking and Hitmonlee just to outmatch Amber
9. A tad obsessed with Amber
10. Loves helping her father with his business stuff
11. Makes her dads' lunches everyday because if she didn't they would starve
12. Not interested in Pokémon research
13. Always training