Add BW2 in-game trades (#1524)

Adds the seven specific NPC trades from Pokémon Black 2 and White 2
(sourced from Serebii):

- Route 4: Cottonee ↔ Petilil (version-exclusive)
- Route 7: Emolga → Gigalith
- Humilau City: Mantine → Tangrowth
- Route 15: Ditto → Rotom
- Accumula Town: Excadrill → Ambipom
- Accumula Town: Hippowdon → Alakazam

To support these:
- Add encounter slot for the BW2 npc-trade method (vg 14, method 36)
- Add Accumula Town location area (no entry existed)
- Add seven new "Give X in a Trade" encounter condition values
- Add encounters and encounter condition value mappings for B2 and W2

The Yancy/Curtis Funfest Mission trades in Nimbasa City are not
included; they accept any Pokémon and depend on player gender, which
needs additional encounter-condition infrastructure not present today.

Author: matthewchoy88

data/v2/csv/encounter_condition_value_map.csv

@@ -22106,3 +22106,15 @@ encounter_id,encounter_condition_value_id
 75100,193
 75101,193
 75102,193
+75103,195
+75104,197
+75105,198
+75106,199
+75107,200
+75108,201
+75109,196
+75110,197
+75111,198
+75112,199
+75113,200
+75114,201

data/v2/csv/encounter_condition_value_prose.csv

@@ -315,3 +315,10 @@ encounter_condition_value_id,local_language_id,name
 192,9,Headbutt Tree (Common)
 193,9,Headbutt Tree (Rare)
 194,9,Headbutt Tree (Secret)
+195,9,Give Cottonee in a Trade
+196,9,Give Petilil in a Trade
+197,9,Give Emolga in a Trade
+198,9,Give Mantine in a Trade
+199,9,Give Ditto in a Trade
+200,9,Give Excadrill in a Trade
+201,9,Give Hippowdon in a Trade

data/v2/csv/encounter_condition_values.csv

@@ -193,3 +193,10 @@ id,encounter_condition_id,identifier,is_default
 192,20,headbutt-tree-common,0
 193,20,headbutt-tree-rare,0
 194,20,headbutt-tree-secret,0
+195,15,trade-cottonee,1
+196,15,trade-petilil,1
+197,15,trade-emolga,1
+198,15,trade-mantine,1
+199,15,trade-ditto,1
+200,15,trade-excadrill,1
+201,15,trade-hippowdon,1

data/v2/csv/encounter_slots.csv

@@ -1486,3 +1486,4 @@ id,version_group_id,encounter_method_id,slot,rarity
 1485,10,7,4,10
 1486,10,7,5,5
 1487,10,7,6,5
+1488,14,36,,100

data/v2/csv/encounters.csv

@@ -69238,3 +69238,15 @@ id,version_id,location_area_id,encounter_slot_id,pokemon_id,min_level,max_level
 75100,16,271,1486,177,45,48
 75101,15,271,1487,177,45,48
 75102,16,271,1487,177,45,48
+75103,21,627,1488,548,20,20
+75104,21,632,1488,526,35,35
+75105,21,659,1488,465,45,45
+75106,21,650,1488,479,60,60
+75107,21,1364,1488,424,40,40
+75108,21,1364,1488,65,40,40
+75109,22,627,1488,546,20,20
+75110,22,632,1488,526,35,35
+75111,22,659,1488,465,45,45
+75112,22,650,1488,479,60,60
+75113,22,1364,1488,424,40,40
+75114,22,1364,1488,65,40,40

data/v2/csv/location_area_prose.csv

@@ -2393,4 +2393,5 @@ location_area_id,local_language_id,name
 1360,9,Oreburgh Mining Museum
 1361,9,Pewter Museum of Science
 1362,9,Floaroma Meadow
-1363,9,Safari Zone Gate
+1363,9,Safari Zone Gate
+1364,9,Accumula Town

data/v2/csv/location_areas.csv

@@ -1244,3 +1244,4 @@ id,location_id,game_index,identifier
 1361,231,0,pewter-museum-of-science
 1362,175,0,
 1363,243,0,
+1364,347,0,