LOL How is Aizen gonna get past the Almighty, and Yama's bankai.
I actually wouldn't be surprised if Aizen past Almighty.
We would need to see what criteria you need to fit in order to be part of SWP. It's possible (my theory) that SWPs are characters that can counter Yhwach's "Almighty". Aizen, Ichigo and Zaraki are for some reason listed as SWP and it was stated that Yamamoto is not part of SWP only because he got soft during past 1000 years.
For example Yhwach lost battle against Yamamoto, 1000 years ago, if he had Almighty, it's hard to imagine that Yamamoto would be able to beat him, considering Yhwach
one shotted Ichibe after using Almighty. On the other hand it would be stupid for Yhwach not to use Almighty against Yamamoto,
why would he not use it and risk to be sealed for next 1000 years? One of the explanation could be that Yamamoto countered it (with special potential that everyone of the SWP has).
One more likely criteria for SWP is to be transcedent being. Aizen and Ichigo reached that stage in Deicide (according to Aizen), Zaraki's reiatsu couldn't be felt when he arrived to fight Gremmy, and Bankai Yamamoto's reiatsu also couldn't be felt in battle against RoydYhwach. Yhwach didn't said anything about Ichibe, who was able to give Yhwach run for his money, and whose reiatsu at one point also couldn't be felt, any indication why is he not SWP (got weak like Yamamoto or something other) and we saw him not being able to counter "Almighty".
Criteria also for SWP could be "being able to beat captain level opponent without full power". Zaraki beat three sternritters in first invasion, Ichigo easily beat both Quilge and Shaz, Aizen in FKT showed to be capable of doing so, Yamamoto defeated 1/5 of Sternritters without even trying. I doubt Ichibe wouldn't be capable of defeating them without his full power, considering his feats against Yhwach, but still he wasn't hinted to beat Special War Potential.
So I wouldn't be surprised if Aizen can counter "Almighty", but I doubt Current Aizen would be able to beat No Almighty Yhwach with Zanka no Tachi and his other Quincy abilities.
