What effect did Pokemon have on the metagame?
Cinderace was one of Natdex's most controversial Pokemon having been suspected twice within a short time period as more and more deadly sets were explored, and for arguably being insanely broken and still staying in NatDex for a while. At the start, Cinderace, really and all the starters in general were all extremely overlooked as they lacked their hidden abilities making them at best niche breakers, at worst completely unviable. Suddenly their hidden abilities were released, with the standouts being Cinderaces Protean clone in Libero, and Rillabooms Grassy Surge + Grassy Glide combination. Cinderace quickly grew to be a top tier threat, especially with the new edition in Heavy-Duty Boots letting it pivot endlessly without punish. Cinderace's myriad of coverage options ranging from Gunk Shot to nail Tapu Fini, High Jump Kick to bop Heatran and Mega Tyranitar, Sucker Punch to prevent Dragapult from RKing it, and Zen Headbutt to remove Toxapex on the switch in, made Cinderace extremely annoying to deal with defensively, especially considering its main "STAB" already had a good offensive typing, and made it easy to wear down softer checks such as Landorus-T and Gliscor. It warped the meta extremely hard around itself, popularising physically defensive Water- and Ground-types such as Slowbro and Rocky Helmet Landorus-T, further boosting the popularity of other, now much less potent threats such as Ash-Greninja and Rillaboom. This singlehandedly popularised the infamous "BlissBro (+Corviknight/Zapdos)" Defensive core, which was arguably the most common core on teams during this time period. The dominance this Pokemon had on the metagame was so large that it made other Pokemon look banworthy themselves just due to how well it paired with it (Rillaboom), or how commonly they were used on teams as a blanket defensive core (BlissBro).
However, this was merely just the start of Cinderace's rampage across the tier... During the start of Cinderace's rise to glory, Pivot sets with Heavy-Duty Boots were what was seen as far too oppressive on teams and over-rewarding they were to use due to how they forced certain exploitable Team Compositions that was too repetitive to be seen as healthy to the metagame. Setup sets utilising Bulk Up or even Work Up were occasionally used on HO's as a breaker that could potentially lure one of Cinderace's checks and potentially break, but sometimes inconsistent and only really fitting well on HO. Soon after NDWC 1 concluded though, a new set emerged from the depths.... Bulk Up + Z Double Edge. This was definitely the straw that broke the camel's back for this blasted bunny, as it demolished every single one of Cinderace's checks with ease after a Bulk Up, not relying on a a specific coverage move or needing an item like a Life Orb to boost damage output while hurting longevity. Furthermore, the Defense boost from Bulk Up is extremely useful on a wide scale, preventing the likes of Landorus-T, Mega Swampert in Rain, and even Mega Lopunny's Fake Out + Frustration combo. This devastating set excelled on HO teams, like the one shown below, which was also turned into a sample team as well!
Heres also a replay from NDWC where this Cinderace set demolished the opposing team:
https://replay.pokemonshowdown.com/gen8nationaldex-1294428140
This specific set flew under the radar for ages, with a whole suspect test for Cinderace went one without much exploration of this set. However, as this set was popularised, cries for another test ensued, and finally the bunny was banished.
In what main roles was Pokemon used?
The pivot set was by far the most popular, and really the only cause of concern for this Pokemon up until the middle of its stay in the tier, where set-up options were more explored, especially on HO. These setup sets were powerful breakers that easily removed at least one important Pokemon from the opposing team, and was extremely easy to be rewarded for using it. Pivot sets were still powerful and oppressive, and really rewarding on common Bulky Offenses that loved the free pivoting on passive checks like Toxapex and Slowbro, but wasn't what shattered the meta.
What caused it to have a significant impact?
The combination of amazing offensive stats, decent bulk for an offensive Pokemon, an extensive movepool to couple with a phenomenal ability coalesce to the monster that Cinderace was regarded as. It having a wide range of options was what initially brought it to light, it had coverage moves for every single one of its checks that were easily slotted on, and later on Norm Z was founded which tore through all its normal checks with ease.
How do/did you deal with this Pokemon in NDOU?
The popularisation of Bulky Waters such as Slowbro and Physically Defensive Toxapex were the main forms of counterplay, both generally sporting a Rocky Helmet to punish Ace's U-turns. Physically Defensive Lando T was also a common soft check on more offensive teams, although it is easily worn down after switching in once or twice to Pyro Ball. On Stall, Alomomola was the best counterplay to it in the tier, Regenning off U-Turn damage easily and chipping Cinderace with its Rocky Helmet. However, all of these quickly faltered once Cinderace clicked Bulk Up and fired off a boosted Breakneck Blitz.
or :seismitoed:, or to consistently outoffense it, which was exceedingly hard to do due to 
often holding a scarf
