So something odd just happened to me on battle spot.
>I have out Aegislash
>Opponent sends in Porygon2, no ability activates
>I switch to Toxapex, Porygon2 Trace activates, traces Regenerator.
Why did this happen? Is it because Stance Change cannot be Traced? I'm bamboozled
EDIT: After a simple bulbapedia search I found that is the reason.
"If all opponents have Abilities that cannot be traced, then Trace will activate when next exposed to an opponent that has a traceable Ability." -Bulbapedia
Good to know!