>>64002172generation designations are pretty useless for the J20.
As a matter of fact it's useless for most chinese indigenous designs.
This was already the case with their missile developments. For quite a while the chinese were leading with long range land based anti-ship missiles that cruised at just above sea level at nigh interceptible speeds. Nobody else really wanted to (or needed to) develop this tech because the US army had no interest in fighting the US navy, and the US navy/airforce had no plans letting anyone else's ships getting close to any US bases. Enemy ships were a minimum concern for US forces abroad.
So in trying to designate a "generation" comparison to chinese anti-ship and cruise missiles from this time period is a head scratcher - they're clearly not going to achieve tomahawk level of guidance, but on the other hand you don't need to have a 1m cep if your target is an aircraft carrier.
The chinese then applied this mission based design paradigm to planes.
Trying to apply multi-purpose roles that american air forces (and by extension, every export customer of the US industrial complex) demand in order to maintain global hegemony to a purpose built plane is kind of like trying to figure out how sharp a hammer is. It's a hammer, it's not a knife, it's used to beat nails in, it's not supposed to be sharp, and trying to make a sharp hammer that can cut wood just makes it shitty at both jobs.
By extension, this makes "generation" assignments a useless comparison. Does it have stealth to assist survivability? sure. Beyond that, what do the chinese actually want it to do? Who the fuck knows, could be air superiority, could be sensor suite, could be CAS missile truck could be all of them or none of them.
A safe bet at this point is that at a bare minimum, the J20 and J35 pair were purpose designed with taiwan, kadena, ford class carriers and their own carrier program in mind.
