I'm currently watching season 1 on Netflix but there are several there, so far not. Where can I still look, legally?
As far as I know only on netflix but there's only one season
Pokémon Company / Nintendo makes many Pokémon episodes available on the official Pokémon website via Pokémon TV. You have to see for yourself whether your desired episodes are included.
https://watch.pokemon.com/de-de/
http://pokemon-tube.com/component/content/frontpage
Give a pokemon tube to Google
Do you actually know when pokemon season 3 will appear on dvd in german