Located in Castelia City, the Royal Unova is a ship that will take you around some parts of Unova. However, this is an exclusive ship, as it leaves at various times only in the night, which are known to change for each season. The Royal Unova will be open for only three hours in the afternoon; otherwise, you will have to try again and board at a different time. The ship also charges 1,000 Poke dollars, but it’s nothing compared to the sights you can see once you board.
In Winter, you can board starting at 4pm; Autumn and Spring, 5pm, and Summer, 6pm. This is because in real life, the sun’s position changes depending on the season. In winter, the sun tends to set earlier because of Daylight Savings Time, causing the ship to leave earlier. In the summer, the sun is out the longest during the day, causing it to leave late.
Once you get on the Royal Unova, you can go out to the front of the ship and see the tour of all the places you will pass by, or you can go in the ship and battle various trainers. Although the trainers do not change that much when you return, the various items you can get for defeating them will change throughout the days of the week.
There are a total of seven trainers on the Royal Unova, and you can challenge each one whenever you want to. Of course, the tour is bound to come to an end, which is why decisions must be made quickly. After you leave the ship, you will receive an item if you fought enough trainers and won. It’s a small item; usually, it will just be something like a Full Heal. One special item you can get is the Rare Candy, which is when you defeat all seven trainers on a Sunday. Keep in mind that you cannot get back on the boat until the next day when you leave.
Now, let’s discuss the tour part of the ship again. Castelia City is in the southern part of Unova, and some very famous landmarks are close by: Skyarrow Bridge and Marvelous Bridge. As the Royal Unova goes along, you can see how hard the game designers worked by gazing at the Castelia City at night, or by looking at both the bridges as you pass by them. As Serebii says, it “fully shows off the game’s 3D rendering engine”. Make the best use of the Royal Unova by just enjoying (your trainer’s) life and take a break from Pokemon battles or running around and hatching eggs. Gaze out under the stars and admire the beauty that is the Unova region. I forgot how you may access to this opportunity: you will find the Royal Unova in the dock right below the Pokemon Center. If this isn’t it, try another dock (it will either be empty or the ship taking you to Liberty Garden). But you definitely can’t miss out on this daily opportunity!