because if that fat pink fluff can be number 8 because it's best use is to spread paralysis then this sweet blue unicorn should be number 9 (should've been number 6 but whatevs) for it's ease in spreading burn by spitting out hot scalding water from it's horn / ass
if you haven't lived in the era where you just slap this mon on offense and balance just so you can break opposing balance and offense, then you should go watch some replays of this mon. it's an absolute beast. sd sets were thrown away in favor of the sheer force life orb boosted earth powers and wide offensive coverages combined with the knock off boost and ability to use CM or RP to alternate between tearing apart stall and offence alike.
3. Mega Mawile.
lastly, it's a toss up between manaphy , torn-t and this. i ended up choosing this because it's simply much more effective at tearing apart teams. mmawile's traits were unparalled, giving you behemoth defensive options as well as offensive options. with steel fairy typing and hyper cutter preventing it's important stat being dropped, it's able to set up safely before blowing things up with full powered iron heads and sucker punches or even utilizing the momentum it gets to set up sub so that you have a wider range of options to fuck your opponent with. defensive rocks set with intimidate were also a thing but rare since most people wanted to use it's offensive set to it's maximum capacity.
overall, it was a mon heavily slept on due to it's lack of speed and was largely seen as an inferior mega lucario that many people only tried out after mega lucario was banned. in the end, it tore up the metagame so badly that people had to resort to passive mons in ou like weezing / arcanine to attempt to burn it but was largely unsuccessful due to the great plethora of partners that gave mmawile a huge boost in effectiveness by absorbing burns which ended up neutering arcanine's and weezine's usefulness in OU since they were there to solely check mmawile and other random rouge threats.
In that case, my votes go to Landorus-I (same reasons as before, balance breaker and insane win condition that forced two "counters" that weren't actually counters) Deoxys-S (the actual God of Hyper Offense, in tandem with Bisharp it made other plastyles very difficult to use, so much so I'm honestly considering making it one of my votes) Keldeo (tbh it's half the reason Amoong and Tang rose to OU and why Weavile and Bisharp haven't torn the tier to bloody pieces yet, besides Mega Scizor. Legit on most of my teams)
1) Bisharp is because it forms half of the DeoSharp core (seriously, this archtype thing is one of the most dumb things ever). While Deoxys is more crucial to these teams, Bisharp's period in the metagame is far longer and it still is one of the most terrifying sweepers in OU.
2) Manaphy, as I mentioned in the nomination, makes Stall and Balance teams almost unviable because of how easily it takes advantage of the passive mons in these teams. Until now, it is still slapped into teams to break through the fat teams that are thriving in the meta.
3) It also had the tools to do whatever it wants; STAB, Sucker Punch, Fire Fang, Focus Punch, Substitute; making switching into it nigh impossible and alongside Aegislash, made most Psychic-types obsolete in the metagame. This is also the Pokemon that almost gave Arcanine a niche in the metagame.