Speculative HA release schedule for Sun/Moon:

Summer Movie Events:

1. Pikashunium and Pikachu in a cap
2. Marshadowinium and Marshadow
3. Unknown?

Pokémon Global Link Competitions:

1. Passimian (for 2018 release)
2. Oranguru (for 2018 release)

Pokémon Bank:

1. Alola Starters with HAs
2. Legendary Beasts with HAs/Tapus with HAs.

Unknown status:

1. Magearna Alternate Color
2. Flame Body Heatran
3. Eternal Flower Floette
4. Various shinies

Other forms:

1. Pumpkaboo Small Size
2. Pumpkaboo Large Size
3. Gourgeist Small Size
4. Gourgeist Large Size
5. Flabébé White Flower
6. Floette White Flower
7. Florges White Flower
8. Flabébé Orange Flower
9. Floette Orange Flower
10. Florges Orange Flower
11. Floette Eternal Flower