I don't wanna be disrespectful but I'm leaning towards a mismatch (in avengers favor). WBH is not stopping/going down/letting up/etc. getting progressively stronger/faster/angrier/healing faster. Just think about it like this, he's inevitably going to match the JL fighter with the highest power level (that's just how Hulk's anger works, not to mention WBH). Do if you have a sun dipped supes, is gonna produce you a Hulk on "sun dipped supes" level (bad news [not to mention SS would be more than happy to absorb all that solar radiation]). And he'll ultimately be fighting multiple fighters among the aforementioned named because anything less than full attention to a WORLD BREAKER HULK is asking for an apocalypse. Parallax is gonna be a tough one and the best chance at the JL taking the W. But a bloodusted SS at full strength and the molecule master Void is who would take care of that threat IMO. That leaves Thor Scarlet Witch AND the Sorceror Supreme to deal with the faster man alive, king of the seas, jonn's alter ego and the first green lantern. Not saying its gonna be a blowout but it's gonna be a blowout. You didn't even account for the mystic aspect you gave the avengers but failed to give the League (big mistake). Strange can end this whole conflict with a snap of his fingers. Give him, the God of Thunder and a full strength SW three days prep time? Only makes things worse. Call me biased if you will but I wanna know how any team with WBH, Void (THE FUCKING VOID), Thor, SS and two masters of mystic arts are gonna lose.
I like the idea of Storm among the names you mentioned. Though I see it having to do with a small team she'll be training and it could even dip into some t'challa/wakanda tie ins. Or maybe an origins story, about the village she was raised in as a mutant worshipped goddesss
There is no bigger threat in the marvel universe than the Phoenix, that is made very clear. When you fuse it with the corrupted humanity of the omega Jean Grey it becomes unfair, literally. Only way to stop the world from starting over in her image is getting to the sweetheart Marvel Girl underneath all that badass Phoenix.
If the infinity gauntlet holds any value in this confrontation then it isn't a hard outcome to determine. Galactus alone is a task with potential to occupy the entire JL (seeing how they're main priority is to protect innocents). Galactus has the ability to end a single planet quite quickly, making him center of focus for high ranking leaguers. Tyrant would be a hypothetical notch below Galactus among the characters named. Created in Galactus' image, he rules an empire that spans galaxies and posseses abilities/attributes similar to that of Galactus to the point where they've stalemated before. A universal threat level at worst (that makes two). Dark Phoenix, again another vicious threat of universal scale. Dark Phoenix has shown us feats such as manipulating matter, altering time, rebirth of course and raising the dead just to name a few. A cosmic entity with the presence to bring a universe to its knees (multiple times), that feeds on living stars, melded with an omega level telepath/telekinetic named Jean Grey. With excellent control over unimaginable power, and in her form, she can easily go planet to planet causing more than enough trouble for heroes to deal with (trouble=protecting, evacuating, preventive measures, even actually fighting) if she chooses to be so tedious. In actuality she can target main stars of solar systems to swallow, leaving the orbiting planets in peril. The Void: counterpart to the man with the power of 1,000,000 exploding suns. The void was created by Reynolds' subconscious as the result of newton's third law. For every act of valor undergone as the Sentry there is an equal and opposite deed committed by the void. Reynolds fears the void with each of these passing transactions making the void stronger each time. Because his powers are held together by his mental abilities the more mentally stable Sentry is the more powerful he is. The more Sentry fears, frets, and worries of the Void the more powerful the void becomes. A planetary threat level at best, the Void will pose difficult and confusing to defeat for any opponent (if Superman had the chance to engage the Void manu y manu--no holds barred--he can be dealt with. Not too educated on Juggernaut's full abilities as Trion from the crimson gem. However I understand his abilities of enhanced superhuman strength and endurance, resistance to mental attacks and his virtually unstoppable momentum. Under the full effects of the crimson gem he achieved power to consistently rip through dimensions (momentum) and it has been noted that he can "take down" Galactus. Though his travel isn't limited to one plane, I'll deem him a planetary threat. He will have to be calmed/slowed down to have a chance at defeating him. Telepathic attempts are null so he'll need to be stopped with pure force alone (good luck with that). Most ppl are unfamiliar with an accurate depiction of the Silver Surfer, Galactus' personal favorite and preferred herald. Embued with the power cosmic the Surfer is completely enhanced to a level above regularly conceived "life." Cosmic awareness grants him knowledge and cognition far beyond comprehension. His energies are fueled and replenished by the cosmos and his relationship with Galactus only amplifies what they are capable of. A planetary (/universal with Galactus) threat level capable of going toe to toe with the best of both (MU and DCU) universes and the ability of making the decision to end planet Earth. The surfer more than likely wont be leaving Galactus' side so that they may better assist each other.
Its hard to be descriptive on possible counteractive measures the DC universe could take to best take this situation (I'd love to, just to be fair) but the outcome in my opinion won't be affected by it.
Mind you, all of these atrocities are being carried out at once. Assuming genius level tactics--courtesy of Thanos--are carried out to ensure maximum efficiency of each character's ability, it will be an overwhelming scenario for DC heroes to combat. Way too many universal threat levels for one universe.