Hey guys.
I'm going to drop my experience here. So far I've used BB-10 and Tornado Attack, alone as well as with a second person present. Later on in the day I will try the Burst Standard Stadium. Don't know if there are different variations or anything, mine comes from B-08. Here is what I gathered:
Firstly, in solo testing, attack types were futile. I tried a variety of ARs ranging from Trygle AR, Driger G AR, Driger V2 and Seaborg 2. A couple of bases, from Defense Grip to Uriel 2 + BK, and even CGB, in case I could create something that could knock it around enough to make WB4 lose by outspin. This was both in BB-10 and Tornado Attack. No luck at all. It was hilariously bad. The attack types came close, but were really just missing that extra oomph. Regularly would WB4 be knocked beyond the tornado ridge but it would never leave the stadium. Truly annoying.
Here is where things get interesting, from what I've seen so far. If you've tested by yourself, you can tell that the AR of the attack type beys generally find themselves in an awkward spot relative to WB4 - typically just scraping the top of Circle Survivor and the Weight Disk. It is so awkward for them as they're almost constantly sour-spotting their hits. This interaction is uniform across the attackers because WB4 is planted in the middle of the stadium and the attackers are always shot second, flowering around the ridge looking for a good hit. This angulation feeds attackers right into where WB4 would want you to hit it. Putting up any attack type vs WB4 seems borderline cruel in this scenario. You just won't get KO's, and even if you get meaty hits in this non-sour spot area, it isn't normally enough, and still get outspun.
This is drastically different with two people. In fact, I have reservations to say that you can get realistic results in this matchup without 2 participants. With all that previous solo testing in mind, as well as not having Manta Diver AR myself, I figured the closest thing to a shot vs WB4 was an OHKO Seaborg 2 based bey. All or nothing, your first two hits net you a KO or you lose. In solo testing it lost, it was down bad, but perhaps there was hope for it during a real battle. I wanted it to be similar to what Wombat put up, too, and I imagine Manta Diver based attackers rely on the same principle of all or nothing, so I went with this:
AR - Seaborg 2
WD - Wide Defense
SG: Neo Left
BB: Defense Grip
Nothing crazy.
So! Now onto the good stuff. Two people launching at the same time means that both beyblades will be gravitating towards the center at the same time. Solo, WB4 gets priority to stick itself there in between launching your attacker. What used to be a near insta-lose the second you chose a WB4 combo was more around the ballpark of 50% for either combo. It was a toss up whether Seaborg 2 would meet WB4 before it made it to the center, meaning during the first 2 flower pattern revolutions where Seaborg 2 is at the height of its KO potential, or not. If it did, this usually meant a KO or lead to a KO since it wasn't a pure sour-spot hit. In one instance WB4 hit one of the walls on my Tornado Attack so hard it still went flying up and out of the stadium. A dope interaction, but this was once out of a good fifty-odd times we battled unfortunately. WB4 deserves more clowning like that. If it survived, as in WB4 did not get KO'd instantly and reached the center of the stadium in the initial few seconds after simultaneous launch, it was essentially impossible for Seaborg 2 to do much of anything, just like in solo testing. Back to the sour-spot jail. This was the same for both Tornado Attack and BB-10, though I think the over-the-wall KO is simply not possible on BB-10, ever. I will do duo testing later in the Burst Stadium, as well as use other combos too. It could be that this small window is enough for other non-OHKO attackers to take advantage of. I have my reservations, but it is possible.
Finally, on top of all this, it also depended where I positioned WB4, though this might seem stupid to have to mention, I want to include it in. I mean positioning in relation to stadium walls, where WB4 was launched. Purely anecdotal and haven't taken the time yet to officially test both configurations, but if I launched WB4 between two walls, as in I was launching right above an exit, it would be much tougher for Seaborg to get a KO even if it landed a meaty hit or two immediately. It wasn't impossible, just felt a bit harder to pull off. Conversely, if I launched WB4 above a wall, with two pockets on either side, it felt a bit easier to get removed from the stadium immediately. Of course there were cases I launched in between walls and still got KO'd, and cases where I launched between two exits but got saved by a wall or made it to the center of the stadium. Again, I'm going to have to do testing with both configurations extensively, it really just might be random or some kind of subconscious confirmation bias.
With all that said, hovering around 50% WR may not seem like much, but it is a hell of a lot better than 10%, or something like that, observed in solo testing. I'll do Burst Stadium later today I think, we'll see.
Edit: just because I forgot to mention it. I couldn't find the original Circle Defenser+Normal Base+Circle Survivor I used way back when Th!nk first introduced this to me, so the EG is stock Wolborg 4. Rest is uniform.