general stuff about forms:
- sometimes an encounter is unambiguously with a specific form
    - e.g. Unown in FR/LG, Shellos, Basculin, Pumpkaboo, regional variants
- sometimes the form is random or unrelated and it makes more sense to list
  just the species
    - e.g. Unown in OR/AS, Vivillon, Minior
- sometimes the form depends on the encounter but is more complicated
    - e.g. Unown in other games



RBY:
- regular encounters while wandering (grass/cave/surfing)
- fishing
- scripted encounters
    - in RBY this always means talking to them on the overworld, but I'm also
      letting this cover stuff like the Pokémon in the Mahogany Rocket Hideout,
      or the Pokémon from the US/UM haunted school sidequest
- received Pokémon (starters, gifts, Game Corner, fossils, etc.)
- in-game trades
    - nicknames per language
    - held items when traded to Gen 2

GSC:
- time of day
- swarms
- Headbutt
- Rock Smash
- roaming Pokémon
- preset IVs
- preset shininess
- preset gender
- preset moves
- held items
- received Pokémon can be eggs
- weekday requirement for scripted encounters
- different encounter list during the Bug-Catching Contest
- Teddiursa/Phanpy are version exclusive but are swapped in Japanese vs
  elsewhere

RSE:
- more terrain types for regular encounters (sand/seaweed)
- preset abilities
    - slot 2 abilities that change if transferred to Gen 4/5 and evolved
- preset natures
- preset contest stats

FR/LG:
- Altering Cave

Colo:
- shadow Pokémon

XD:
- Poké Spots
- preset nonshininess

D/P:
- Pokéradar
- dual slot
- Honey trees
- Pokémon from PBR/Ranch/Ranger
- faulty preset nonshininess (Manaphy egg)

Pt:
- defeated legendaries reappearing, sometimes in different places

HG/SS:
- Hoenn/Sinnoh Sound
- Headbutt (different from GSC)
- complicated Safari Zone
- Pokéwalker
- Brock's Rhyhorn has one preset move and three determined by level
- three different encounter lists for National Park (regular, BCC, postgame BCC)

B/W:
- seasons
- shaking spots etc.
    - Bulbapedia calls these "phenomena"
- more terrain (dark grass, puddles)
    - separate encounter lists per terrain in the same area
- White Forest
- Dream Radar

B/W 2:
- N's Pokémon
- Hidden Grottos

X/Y:
- hordes
- more terrain (flower colours)
- trash cans
    - I think this can probably be lumped in with B/W's "phenomena"
- Friend Safari
- *semi*-preset IVs

OR/AS:
- new encounters everywhere with the National Dex
- sky encounters
    - phenomena again?
- DexNav

S/M:
- separate encounter lists for individual grass patches
    - not even separate terrain, just the same kind of grass
- ambushes
    - can this be lumped in with phenomena?  scripted encounters?
- SOS call
- Zygarde Cube
    - can I call these received Pokémon?
- Ultra Beast missions
- Berry piles
    - phenomena again?
- Island Scan

US/UM:
- Ultra Space shenanigans

Let's Go:
- can see spawns on overworld