I actually killed an Arceus with a Wigglytuff using Counter, and used some FEAR Pokemon in ubers. It was a joke though and the team was not intended to win.
I recently saw a Focus Sash Breloom with Spore, Focus Punch, and Swords Dance. I let it kill sleeping 2+ Scizor (as I had Jolly 252 speed Mamoswine waiting in the wings to force it out or kill it with Shard, and it switched out at 1 HP) as I was hoping it would wake up to use Bullet Punch since I did not want to switch in to a potential attack (I had the bulky pivot Landorus-T too). The set seems absurd since he forfeited his priority move Mach Punch or his STAB technician Bullet Seed in order to use Focus Punch, presumably on a hapless switch in or sleeping Pokemon.
It may have some merit as a tactical surprise though since it can overwhelm even a fighting resist switch in or a physical wall. It OHKOs (ha ha; Rock does some damage to break Sturdy) specially defensive Skarmory and has a 6.25% of inflicting > 100% on the physically defensive variant. Again, this tactical surprise comes at the cost of either sweeping ability (even 2+ Mach Punch would not score critical OHKOs without being boosted by Life Orb) or coverage from Bullet Seed. After one knows about Focus Punch, it seems easily to play around something that relies on negative priority move to inflict immense damage.
Regardless of its merits, it just seems Swords Dance Terrakion (with a Focus Sash) is more reliable. Just watch out for priority though.
He also had a Blissey with Thunder (on my Jirachi) and Aromatherapy on a rain team, but that Blissey had Natural Cure, not Serene Grace as I paralyzed it before and it came back without paralysis. That could be a mistake though. Natural Cure seems somewhat redundant with Aromatherapy (Blissey does not care much for burns or paralysis as she does not run physical attacks and she is slow anyway, although it is useful if it is sleeping though and she does not have to use a turn to heal herself from Toxic as she can just switch out) while spreading paralysis with a 100% accurate Thunder is more valuable to support the team and also has some surprise value as Gengar lure.
I actually think that may be a good idea, since it can punish a physical sweeper that attempts to use Blissey at set-up bait (as I did with Scizor in the rain since he lead with Politoed and I had no weather, but he switched out into Gengar, presumably expecting a Superpower).
Edit: The damage calculations show that this would not be a good idea since Thunder only does about 33-39% damage on Gengar with no Special Attack EVs on Blissey or Special Defense EVs on Gengar. This is about 83 to 100 HP for a Pokemon with a low base special defense 75 and base HP of 60 and total HP at level 100 of 262. For a Pokemon with a base 100 Special Defense and no investment, it would do between 65 to 78 HP if it was neutral to Electric attacks. It would not substitute for Seismic Toss as a means of inflicting damage (since it would involve an extra turn or more to kill something with Thunder as opposed to Seismic Toss, although one may get a free turn or two due to paralysis) or the 100% paralysis of Thunder Wave, as the paralysis interferes with the Toxic Stalling tactics of Blissey/Chansey. There are more reliably ways of spreading paralysis for a team or inflicting damage with Blissey.
Here's the Replay...
http://pokemonshowdown.com/replay/ou-50290077
Also, the using the damage calculator, the Blissey seems to have no physical defense Evs since it took about 40% from Jirachi's Body Slam (the damage calculator says it should do about 20% with max physical defense investment) while his Thunder did 22% to Jirachi (252HP/168SpeDef Jirachi) suggesting it has max Special investment.