Wait, so you're saying that because Dark plays online that he's not an authority on The Joker? Or that he's less skilled as StevO is? That's kind of the implication, isn't it?
The cornering is not inevitable if Batman is on point with his zoning, especially if his combos are ended as I described. Gunshot delays are cute and all, but only really effective if Joker has the lead to begin with. Otherwise, they either trade or Batman wins if he spends the meter. Meter which, on block, nearly guarantees more zoning. It also largely depends on how Batman string staggers as to whether or not it will be interrupted. For example, Batman has B1 which is neutral on block. He could continue the string, trait cancel(Admittedly not the safest but if Batman can block a Lex Corps Charge after b11 xx trait, he can block a d1), MB Batarang into more pressure/throw(again, back to full screen for Joker), etc. And again, he can use his trait in zoning(although zoning is not my preferred use for trait in most situations because they're pretty poor projectiles). Joker's one-hit gunshot pales in comparison to Batman's two-hitting, mid projectile, let alone with trait assisting.
I've already stated that Joker excels in the MU with his jump attacks and corner game. But Batman can avoid being cornered, and he can put Joker full-screen at the end of every combo and continue zoning.
Joker loses this match-up, Qwark. I know you're a match-up cop and feel the need to convince the community that Joker is secret S tier, but the tools are the tools.
More importantly - why would you be arguing a point difference between 7-3 and 6-4? That's nearly as bad as when Ra Helios tried to argue Catwoman beating Batman in a 5.4-5 match-up when I was insisting that it was even. Are we wanting to argue the .4(or in your case, the 1 point)? Does it really matter?