Since I haven't worked on the quest, I'm going to give my opinion as a player. And honestly, I'm very disappointed in the quest.
I already knew that beforehand, but right from the trailer, we knew the quest was supposed to be inspired from the Zelda serie. However, the quest itself failed to deliver on this inspiration. I heard we would have dungeons, but what we got was just huge mazes. Zelda mazes are typically puzzles.
Normally, a typical Zelda dungeon, you enter a dungeon, you figure out how to progress through rooms with what you got, you get a new item which allows you to access new rooms, you find a map, a compass, keys, eventually the boss key, all while solving puzzles to be able to progress until you reach the boss and defeat it.
We had none of that. It was just large mazes. I quickly followed the right hand rule to avoid getting lost, found random stuff we needed to find, then found the boss. There was no puzzle, and it didn't take very long before I got the urge to search for a map of the area.
The maps were also unnecessarily huge. If you are to make huge maps, you need to fill it with stuff to do. Side quests, items to find, fluff NPCs, just, anything to reward exploration besides the main quest! But there was nothing. Just dead ends.
This problem of huge maps is further amplified by the Mountain boss. It didn't happen for the Forest boss, but for the Mountain boss, if you lose, you get sent back to the Pokemon Center. And then have to walk aaaaaaaall the way back through the huge maps and mazes. I'm normally very patient and never use repels, but I've lost it, and cracked open a bunch of the repels that were laying in my inventory.
The bosses were rather hard, specially since you couldn't use items. For a legendary quest, that is fine, you don't want to give legendary Pokemon for free. But as an event quest, it just doesn't work. Events are supposed to be available for all players, but this is a huge barrier for the players that haven't had the time to optimize a boss team.
The trainers on the way were also made on the hard side. Every battle, I would lose around half my team, and find it better to use an Escape Rope to return to the Pokemon Center, rather that use revives and potions to heal my team. I was honestly hoping to see an healing point somewhere so I wouldn't have to go through the hugetastic map again, but I was disappointed to find none.
Also, we're used to completely ignore the Pokemon roaming the routes. In the Wasteland, the first thing I did was to talk to, I believe, the Garchomp, but just out of curiosity, nothing happened, and I moved on. I triggered the cutscene with Keldeo, and then moved on, trying to find my way. Only when I finally reached the end, did I learn I actually had to go back and talk to the roaming Pokemon, even the one I already spoke to before. I was annoyed since I was already getting lost in the huge map.
I've also seen from a guide that the reward from the present in Matsuki would have worse rewards if you had not completed the quest. This is an extremely bad design, as it means you get penalized for exploring before doing the main quest. Normally, you rather want to reward players that explore. If you penalize them instead, they'll just want to follow guides in order to not get penalized.
Finally, staying away from the gameplay elements, but rather into the story... I honestly didn't really like a few of the elements. I've never liked self-inserts inside story, like Chappy in Johto (They're fine as side NPCs). And seeing the hero being Niko (as in our Admin, Red), it just doesn't work for me.
There were also a couple dialogs that I didn't like. The two main examples I remember were:
- After defeating a Tyranitar, it said it returned to Mt. Silver. But how? How did the Tyranitar even get on Matsuki island, and why did it go there? I remember that something attracted Pokemon, but if it even attracted a Tyranitar from a completely different region, then why don't we have a huge swarm over there?
- At one point, my character said she shouldn't have eaten perished Oran Berries. I know you were trying to be funny with that line, but personally, it instantly breaks the immersion, as I see my character to be someone that's very careful, and wouldn't have eaten something perished. This is why all games that allow you to customize your own character makes you either completely quiet, or only talk via choice dialogs.
Regarding that last point, that's also going against the Zelda reference, since Link never really speaks.
This is all of the feedback from me. It simply didn't live up to the hype you tried to rise from the trailer, in my opinion, and I'm already hoping for a rework of the quest.