Aggressive Defense. These days, people tend to associate aggression with Attack types, while completely excluding it from the field of Defense, which, as this testing hopefully shows, is a false and hindering mindset, especially when it comes to tiering. Most players' definition of Defense nowadays is the "one that sits still and takes hits really well." That really isn't the case, however. Our definition should be (in my humble opinion - one I think we'll all agree with), the "one that avoids being KOed" (of course, you still have the matter of consistently out-spinning your opponent, but that's more an essential element of customization, rather than an attribute of "Defense" itself). That said, this combination aims to utilize the aggressive properties of RF to neutralize an opposing Attack combination through extremely high traction and momentum.

First off, RF provides more traction than conventional Defense Bottoms. Its surface area is is significantly broader, which makes for an extremely high level of friction between the Bottom and the stadium floor - and essential attribute of any competitive Defense custom. Not only that, but RF also provides aggressive movement, which is honestly the most significant advantage Attack types have over conventional Defenders when it comes to direct collision. By more or less neutralizing this advantage by applying high speed and momentum to the Defender, we come out with a much higher win rate against Attack Beyblades. In a nutshell, seeing as almost every advantage an Attacker has over a given Defense custom is provided by the Bottom it uses, we can simply nullify those advantages completely by using the same Bottom on the opposing Defense combination.

That said, I do believe that RF-based Defense is extremely deserving of top-tier status, due to the very impressive numbers it's shown me so far (especially compared to the run-of-the-mill stationary BD145 Defender). This is a combination derived from the concept that I hope will demonstrate its overall effectiveness (not only of this particular variant, but of all Rubber-flat based Defense types).

MSF-H: Heavy weight. To maximize the level of friction between the Bottom and the stadium floor, we need as much weight as possible. This is an essential element of any Defense Beyblade.

Genbull: Genbull is a really cool Wheel. Not only is it the best Stamina Chrome Wheel available (which makes it eligible for this setup, as even on RF it can still easily out-spin our current competitive Attack combinations), its Defensive capabilities are off the charts. If you ask me, it completely outclasses our friend Revizer (especially as I've found it harder to KO on top of having superior Stamina, presumably due to the optimal weight distribution/level of balance that Revizer clearly doesn't have). I'd say Genbull was practically made for this setup.

BD145: Weight, bulk, and a lowered center of gravity (along with slightly higher capability against left-spin Attack types at low RPMs). BD145 is the heaviest Track in the game, and it fits this custom very well.

RF: As stated in the OP, the goal of this custom is to neutralize an opposing Attack combination's advantages of speed, higher traction and momentum, by applying the same part that gives those advantages ourselves: an RF variant. We use RF (rather than R2F/LRF) for its superior Stamina, since we obviously still need to out-spin the Attacker after we've avoided the KO to come up with a win.

Against Right-spin Attack types, bank hard. Not too hard, but harder than you'd launch a normal Defense types, since we still do need to worry about out-spinning our opponent (which shouldn't be too difficult, but we are still dealing with an RF variant here, and you can never be too careful). I would suggest around 90%.

Against left-spin Attack types, I would honestly launch at full power. I've found that launching lightly, even at 80%, makes it much easier for the opposing combination to push you around. You need to stand firm coming from the opposite direction, or they'll just slip you over diagonally and roll you right out of the stadium. You wanna be able to meet them directly, take the hit well and deliver your own, suffer as little recoil as possible, stay fully upright, and immediately jump back and hit them again to break their Attack pattern. You have the weight advantage, so shoving them around shouldn't be too hard if you launch as hard as they're launching. Whether or not to bank really comes down to preference, but I would personally suggest going for a straight-up tornado stall, so as not to put yourself at a tilted angle and make yourself vulnerable to push-KO.

Against other Defense combinations or Stamina combinations, launch at maximum power, and go for the KO.

Benchmark:
Vs. Attack:
Vs. Defense:
Vs. Stamina:
Vs. Balance:

[MSF-H] (Revizer/Killerken) Dragooon (SA165/BD145) RDF
MSF-H Revizer (Killerken/Genbull)/ Genbull Genbull BD145 (RDF/RB/RSF/CS)

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3) Genbull KO
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17) Duo KO (Genbull Self-KO)
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