If a Ninjask with 400 speed used Agility it would be boosted to 800 and it used Baton Pass and sent out Slaking would Slaking have 800 speed or would his speed stat be multiplied by 2?
When you use an agility, it raises 2 stages(x2 speed) so when you baton pass it to Slaking, he get the 2x speed boost. Click here to read on Baton pass.