Ethereal_Writer
I feel like Zorua would be a great starter, I can feel that the bond that they could develop in the future can be incredibly deep. For the other Pokémon, Honchcrow is a really cool one quite possibly the most swag out there, not to mention it is able to counter bug and fighting Pokémon. Bisharp is a good choice in the case of fairy type Pokémon, also very swag. Absol is a fan favorite Pokémon with a good mega evolution, I also love it's design. Maybe late story when he gets strong he could train a Hydreigon as those are very powerful dark dragon Pokémon. As for the final Pokémon maybe you could set up an event in where he could catch a Darkrai.
1- Drapion (poison/dark) weakness (Ground) 2- Bisharp (Dark/Steel) weakness (fire/Ground/Fighting) 3- Zarude [semi-legendary] (Dark/Grass) weakness (fire/fighting/fairy/flying/ice/poison/bug) 4- Hydregion (Dark/Dragon) weakness (dragon/fairy/bug/fighting/ice) 5- Incineroar (dark/fire) weakness (fighting/rock/ground/water) 6- urshifu-single kick (dark/fighting) weakness (fairy/flying/fighting)