So, the problem here is the quest is bugged. Here's the story.
I actually completed the normal mode last year, and this halloween I decided to try again the hard mode. Unfortunately, after I lost my first attempt, the quest bugged and I was told by the game to contact the staff. I got this text before I entered the 2nd portal (the portal to battle zone). I ignored it, and thought that it was something small. I kept on going and picked up the 4 pokemons in that battlefield, and start playing the quest game, to find out that it does not work (the message to report appeared again). Alright then, I then just surrendered, thinking that it was just a small bug. Now my team has those 4 pokemons, replacing my actual pokemons in my team. After I checked the PC, my pokemons are there, so I was relieved that 4 of my pokemons didn't just disappear.
So, in conclusion, the quest is bugged, I can't play it, and I got 4 quest pokemons as a bonus. (Look at OT) Thanks!