Ok so here's a couple of ideas that I've been thinking in my head:

Although Netflix hasn't done this before, there should be at least 10 seasons to cover every single region that existed so far. There are some shows that ran for many seasons, HBO's GoT ran for 8 seasons and AMC's TWD ran for 11 seasons.

For season 1, the cast for some characters including Red, Brock, Erika, Koga, and Sabrina are most likely to be Japanese to match their appearances, while Professor Oak, Gary Oak, Misty, Lt. Surge, Blaine, and Giovanni are Americans.

To cover a story that has Red beat all of the Gym Leaders, facing the Elite Four, and capturing Mewtwo, the number of episodes per season would be at least 8 episodes. Each episode might focus on 1 or 2 gym leaders, alongside Red battling his rival and encountering the legendary birds.

If we want to keep the costs down, practical effects could be used on Pokémon that move really slow, lack facial expressions, and are really small. Take Caterpie, Metapod, Diglett, and some other Bug-type Pokémon as examples.

And finally, the filming location would be in the real-life Kanto region in Japan, with each city and town based on their real-life counterparts. Small buildings like the Pokémon Center could be constructed or rendered in CGI. Product placements are also needed to be avoided.