This might be the wrong forum but, I’ll ask anyway.
How is Moonberry in the Emerald Dream when Ysera needed Malfurions sacrifice to crossover?
Also, if Moonberry can be there, why can’t Malfurion?
It seems like Malfurion was robbed of an awesome moment of the Emerald Dream zone…
Moonberry isn’t mortal.
Malfurion is a mortal. Moonberry is just made up of Death magic. She’s not a mortal soul.
Real question is…why is she and or Aliothe always the ones leading an offensive when they’re not even military figures?
Moonberry is immortal and has tricks it knows how to get around
Ok thanks. Its still leaves me with some questions, like how, specifically is she able to cross between the Shadowlands and mortal world on a whim. That doesn’t seem like something the Winter Queen would be too keen on…
That’s where it gets all sorts of weird. LOL The Dream isn’t the mortal world. It’s a plane all on its own sort of like the Shadowlands, but not really, and Ardenweald and the Emerald Dream are connected to each other. I assume Ysera brought her over to help.
The Dream is a complicated place. It’s the blueprints of Azeroth when Freya was helping to shape the world. It’s layers of a parallel realm and what Azeroth would be like if it were never touched by mortals.
They then linked Ardenweald to the Emerald Dream as the realm where the Wild Gods go to rest and be reborn into the Dream and then into the mortal world.
And now, that tree is part Ardenweald and part Emerald Dream. It’s got the magic of Elune and Winter Queen and the souls of the Kaldorei. It’s a special snowflake!
I’m not sure if what I said made sense to you, but I’ll do my best to clear it up if I made a confusing mess! 
I figure that after the souls-to-the-Maw mixup, the leaders of Ardenweald and the Emerald Dream decided they needed to keep in touch a little better. So I wouldn’t be surprised to see a few exchange trips happen from time to time.
Kinda weird since we didn’t get special skybox or effects when we die there, feels like a regular zone in Azeroth
So you’re saying it feels too “natural”? 
The Emerald Dream is one of the Gardens of Life just as Ardenweald is one of the Shadowlands of Death.
The Winter Queen specifically sent Moonberry to the Emerald Dream to help the World Tree’s growth.
Furthermore Malfurion is specifically taking the place of Ysera who was specially bound to Ardenweald by the Winter Queen to make sure she got use out of her.
Moonberry is really Chromie in a moth suit.
I call her Chromeberry and she’s very dangerous and will staple moth wings to you if you’re not paying attention.
Ysera was a special case, as stated like 3 times during the quests. Because she was personally saved by the Winter Queen, her spirit was bound to the Winter Queen and Ardenweald. So she can never leave Ardenweald.
If you watch the scene where Malfurion takes her place again, he also specifically states Ysera’s time to die was not in Val’sharah, and he was supposed to take her place, implying he was meant to die in Val’sharah, not Ysera, but something (I assume an infinite dragon) messed something up.
Well, you see… I love Moonberry… Actually that’s not a valid reason, but I do.
Moonberry didn’t die and get attatched permanently to Ardenwealde like Ysera and Aliothe were.
They’ve been stopped from following the normal paths but Moonberry is just a creature of that realm. She can go wherever with some effort.
Leaders do what they need to.
Aliothe fought the Legion on her world and is powerful. Moonberry is basically the right hand of the Winter Queen.
Well she’s currently not trying to steal and kill your soul with party hats.
because plot armor and bad writers wanting a stupid fairy in the game
That whole thing made me so mad. If it really wasn’t supposed to happen that way then why not just make a Caverns of Time quest or dungeon where we fix it? Instead we have this BS “now Malfuion is sort of dead, and Ysera is also sort of dead, and we need a new aspect because Ysera is still an aspect but not exactly not because she’s sort of maybe a little bit dead”, thing going on now.
She was a soul. Moonberry is just a native of the dream / ardenweald not connected to any mortal soul.
I still did a “wait whut?” double take seeing her but eh it made sense