Hiker (Gyarados for Magikarp Trade)
Constant: 174
Maid (Anything for Eevee Trade)
Constant: 177
Values:
0: Never Spoken
1-3: Spoken
4: Ready to Trade
5: Trade Complete
Other stuff that should be in a different thread but I'm too lazy:
Chosen Starter
Note: This affects stuff like the Shauna Starter Trade. To change the bird that appears post-Elite Four, the constant must be set BEFORE the post-credits save.
Constant: 48
0: Chespin
1: Fennekin
2: Froakie
Shauna Starter Trade Complete
IsSet: 0094
Legendary Birds
No idea how the legendary birds 1-10 encounter count is tracked, but for my test case with Articuno:
On 10th encounter, Articuno moves from route to Sea Spirit's Den. Apparently, no flags or constants changed.
On entering Sea Sprit Den, Unset 0822, 230: 0->1.
On catching Articuno, IsSet 0822, 230: 1->0
While INSIDE Sea Spirit's Den, setting the following value will cause Articuno to appear by walking into the center, no flag required: 230->1.
Update: This (230->1, 0822) is the same for Zapdos and Moltres. The game is somehow figuring out which bird to give but I can't find where that value is stored.