After probably over a year of telling people "Quetz is actually good take my word for it" I finally got around to doing formal tests on it lol. Despite being top tier back in the day it's been super neglected in Limited compared to its contemporary Pegasis for whatever reason. In my experience it's a viable Attack Wheel and a candidate for the Limited Top-Tier list.
Equipment & Procedure
BB-10
Beylauncher L & Beylauncher R
Non-Attack Types always launched first
All Right Spin combos Weak Launched vs Dark Knight, except Quetz which got a moderate launch
In the Attack vs Attack test I alternated launches
Attack types Sliding Shot vs Defense/Stamina, Stalled vs Attack
Vs. Defense
MF-H Quetzalcoatl 85RF vs MF-L Jade Escolpio (Defense) 85RSF
Quetz: 15 wins (10 KO, 5 (Upper) OS)
Jade: 5 wins (3 KO, 2 OS)
2 ties redone
Quetzalcoatl win rate: 75%
Quetz is unique in the sense that it has the lowest reaching slopes of all competitive Limited Attackers - it was able to get underneath even Jade 85 and lift it out of the Stadium (actually over the wall twice) with pretty good consistency. Even if it didn't get the KO, it was sometimes able to pull of what I call an "Upper OS", in which it lifted Jade early in the match and caused it to scrape to death from being so off balance.
MF-H Quetzalcotal 85RF vs MF-H Scythe Pegasis II R145RSF
Quetz: 14 wins (11 KO, 3 OS)
Scythe: 6 wins (2 KO, 4 OS)
3 ties redone
Quetzalcoatl win rate: 70%
Now for a benchmark with the current (for now) best Upper Attack wheel in Limited, Dark Knight.
MSF-H Dark Knight Girago (Crystal Up) 85RF vs MF-L Jade (Defense) Scorpio 85RSF
DK: 5 wins (3 KO, 2 OS)
Jade: 15 wins (1 KO, 14 OS)
2 ties redone
Dark Knight win rate: 25%
Shamelessly stealing Cake's exact setup since I'm not as experienced as he is with Jade. As expected, DK really couldn't move Jade much once Jade was weak launched, and even with Girago it lost the Spin Stealing match all but one time (it's other OS was a "Smash OS", another term I coined as the opposite of an "Upper OS").
MSF-H Dark Knight Girago (Crystal Up) 85RF vs MF-H Scythe Pegasis II R145RSF
DK: 18 wins (11 KO, 7 OS)
Scythe: 2 wins (1 KO, 1 OS)
Dark Knight win rate: 90%
Dark Knight definitely had the advantage here being Left Spin (Scythe might have gotten a few more OSes had I used TR145 maybe), but what's interesting to note is that DK and Quetz KOed Scythe the same amount of times.
Vs. Stamina
Since Quetzalcoatl seems to handle LTDC and MTDC pretty well, it only makes sense that it would fare much better vs Stamina combos of the same height. So I decided to test HTSC since Quetz might have problems reaching it.
MF-H Quetzalcoatl 85RF vs MF Earth Sagittario II 230MB
Quetz: 4 wins (all KO)
Earth: 16 wins (all OS)
Quetzalcoatl win rate: 20%
After seeing that 85 was clearly too short to deal with taller combos, I decided to try D125 and AD145 as substitutes for CH120, since my CH120 no longer stays at the 145 height for the duration of a battle and is super shaky. Only did 10 rounds for each height though.
MF-H Quetzalcoatl D125RF vs MF Earth Sagittatio II 230MB
Quetz: 3 wins (all KO)
Earth: 7 wins (all OS)
Quetzalcoatl win rate: 30%
MF-H Quetzalcoatl AD145RF vs MF Earth Sagittatio II 230MB
Quetz: 4 wins (3 KO, 1 OS)
Earth: 6 wins (all OS)
Quetzalcoatl win rate: 40%
There was one super weird battle where MB precessed around, but like hopped as it was doing so. Once Earth scraped, it rolled into the wall, bounced off, and gave Quetz a random critical hit that caused it to wall save and lose what little spin it had left while Earth was recoil KOed from the hit lol.
And the benchmark with Dark Knight:
MSF-H Dark Knight Girago (Crystal Up) 85RF vs MF Earth Sagittatio II 230MB
DK: 14 wins (12 KO, 2 OS)
Earth: 6 wins (all OS)
Dark Knight win rate: 70%
Vs. Attack
Finally, I decided to back up a statement I had made earlier about Quetz matching up super well vs Dark Knight.
MF-H Quetzalcoatl 85RF vs MSF-H Dark Knight Girago (Crystal Up) 85RF
Quetz: 13 wins (10 KO, 3 OS)
DK: 7 wins (3 KO, 4 OS)
4 ties redone
Quetzalcoatl win rate: 65%
Probably not as one-sided as I made it sound in the Winning Combos/Ban List Discussion/Top Tier List thread (I forget where I made this claim lol), but this might be one of the rare situations where an Attacker wins a matchup more consistently at tournaments than in testing since both Beyblades are launched at the same time.
Despite being on the same height, the shapes of the two Wheels are very much in Quetz's favor. It is able to scoop up the raised Dark Knight with its slopes and KO it pretty effectively, and even glancing hits can mess up DK's lateral plane (Don't know what it's called, but basically so it isn't standing straight up and down with the stadium) enough to make it skip the Tornado Ridge and Self-KO.
So in my experience it seems that Quetzalcoatl's Upper Smash is on par with Dark Knight's Upper Attack in terms of power, but Dark Knight still has better range. While Quetz needs CH120 to KO/OS 230 height opponents with some consistency (and switching to CH120 makes you lose some power vs LTDC), on 85 it is much more effective vs LTDC. Additionally, it performs well vs Dark Knight, and while I haven't tested it vs other Attackers, the strategy it uses to defeat them probably works similarly well. So yeah basically just another LTAC Wheel, but IMO it's one of the better ones.