I started with a Specsjolt that was doing well (got up to 86and started with the biggest threats like Steel/Ground/Rock) but the Focus Sash Pokémon were irritating me so I decided to play that game with a Pokémon who was promoted to Ubers because of surviving a turn to setup on a regular basis. That Pokémon is Yachechomp, but instead of using the Yacheberry, I decided to switch to something a little more reliable because I don't have to worry about spikes or stealth rocks....Focus Sash Garchomp. It only took me 3 times to get through towards the 170 goal (first loss was to a Yanmega and second was Hypno that kept me asleep for 4 turns and inflicted me with nightmare).
1. Pokémon: Platinum
191 win streak
2. Garchompr: Focus Sash, Jolly, 252 Attack, 252 Speed, 6 hp.
3. Well, since it's battle hall and Garchomp, I think the strategy is pretty obvious. Hit 'em as hard as you can and if they some how manage to survive (Dewgong is one in particular that I recall consistently surviving the first attack), the Focus Sash would ensure I would get a second attakc that would usually finish off the opponent.
4. Turn 1-Garchomp uses Outrage and inflicts approximately 58% or 59% (I remember it was enough that the HP was just barely still orange after leftovers). Snorlax uses Crunch (Crit Hit and defense drop) that results in a loss of 65%. Snorlax recovers with Leftovers.
Turn 2-Garchomp continues outrage and Snorlax survives by a single pixel and uses Crunch again to finish off my Garchomp. I'd definitely say it was that "just enough nudge" of luck that ended my streak because that crit hit + defense drop of crunch or the same damage as the first attack would have taken down the Snorlax.
5. Other Pokémon that I considered a dangerous threat for this Garchomp were:
1) Yanmega (Bug Buzz + Speed Boost + the good enough defense results in Yanmega reliably surviving either Outrage or Fire Fang and then the Speed Boost makes it faster on the second turn to finish the job)
2) Cloyster (Skill Link + Icicle Spear + 180 base defense can help it survive the first attack and return 5 Icicle spears...however with that mere base 50 HP, it can still be OHKO'd)
3) Bulky Pokemon that can survive one attack and put Garchomp out of commission (one I found particularly noteworthy example is a bulky Hypno that survives the first attack and puts Garchomp to sleep)
4) Speedy Focus Sash-ers that can 2HKO Garchomp (I did not see a Weaville with Ice Punch and Ice Shard but it would be able to get the job done)
5) Using Fire Fang and missing (in particular Abomasnow because of the 100% accuracy blizzard and the snow warning to finish off the Focus Sash survivability)
And since I'm not that well known yet on Smogon, I've enclosed a link to a picture of the records as proof of my streak.
(Note: I know it's not the best or clearest picture in the world because of the DS backlight and will remember that for future pictures, but the full-size does show the Battle Frontier location, that it is singles, that it is Garchomp I am viewing and that the record streak is 191).
Now onto a new facility...probably Battle Factory.