Might sound a little crazy but Ambipom can effectively run a special set with Nasty Plot, It has a very good special move pool coupled with technician
[Set]
Name:Special Sweeper
move 1: Nasty plot
move 2: Swift
move 3: HP Fighting/ Baton Pass/ Water Pulse
move 4: Shadowball
Item: Life Orb
Ability: Technician
Nature: Modest/ Timid
evs: 252 spatk/ 4 def/ 252 spe
The Primary move for slot 3 would be HP fighting @ 59 damage for the technician boost but Water pulse hits Rhyperior for 4x super effective and hits steels for neutral and has chance for confusion, and baton pass is just so you dont waste a nasty plot if something you cant handle comes in.
It gets alot of KO's on pokemon that dont expect this and at least deserves an OO mention.
The problem with this is that Ambipom is so frail, he finds it hard to set up. Throw in a weakness to the common Mach Punch, and vulnerability to almost all priority moves, and it becomes less promising.
Then, consider that there are MUCH BETTER Nasty Plot users in the tier, and there is almost no reason to use Ambipom in such a role.
.....at least, that's how I feel.