Does Unburden and Agility affect the speed stat separately?

Question

I'm trying a new combo, using these mons:

Drifblim @ Sitrus Berry
Unburden
Careful Nature
Stockpile, Minimize, Baton Pass

Into

Ninjask @ Focus Sash
Speed Boost
Jolly Nature
Protect, Swords Dance, and Baton Pass

And finally into

Aggron @ Aggronite
Sturdy/Filter
Careful
Brick Break, Rock Slide, Earthquake, and Heavy Slam

So my Mega Aggron has a base Speed stat of 102 at level 50, which means that after +6 Speed Boost, the speed would be at 408.

So how would Unburden affect that? Would it double the stat to a stupid speed of 816? Or would it raise it by 2 stages, making it 510?

Answer 1

Aggron's speed would still be at 408, because you can't Baton Pass the boost of Unburden.
I tested using Accelgor, so I can get Unburden to activate more quickly with Super Fang, as shown in the replay.

Replay