I’ve spent most of the time trying to catch the three legendary lake Pokèmon. Before that, I realized I was missing a Rotom and a Tentacool. The first one, I missed because I was going through Eterna forest during the day, but the second one, I don’t know how I missed.
Anyway, after catching Rotom and defeating a Tentacool, all I was missing are the three lake Pokèmon. I managed to catch the first one easy, but the second took a long time. I had to waste about 40 dusk balls to catch it, but in the end, I got it. The third one, Mesprit, ran away, so I now have to chase him all around the map. I did get his entry in the Pokèdex, so this means the Pokedex was completed.
I reported this to professor Rowan, so professor Oak arrived and upgraded my Pokèdex to national level. I hope this means I get to catch all of the original 150 Pokèmon.