I did this for the first time with Moon and I didn't really like it... I thought I would. Who wouldn't want to know which of their favorite Pokémon were available? Who wouldn't look forward to kicking butt with a premeditated team for maximum fun factor?
But when I actually did it, I don't know, it didn't work for me. I think choosing my own Pokémon makes me play it too safe. It makes me only use powerful Pokémon that make the game too easy and more predictable. I ended up abandoning that playthrough and did something weird instead.
Basically, I would catch every new Pokémon I found, so I always had a massive and unorganized haul of Pokémon in my PC. Every time one of my team members reached its final evolution, I would box it and replace it with something else that still needed to level up. This meant I was always using new Pokémon, and always checking which TMs they could learn, and very quickly filling my PokéDex by always seeing an evolution line through. Towards the end of the game I'd found a team of five I really liked and stuck with for the Elite 4, but then I continued to rotate out a low-level Pokémon who needed help leveling up.
I'll probably do that again.
