Hello and welcome :)
Regarding your question, not necessarily. You can only start a new game if:
1st - your game is corrupted;
2nd - the map where you last saved the game before updating has been modified and you can't exit; or
3rd - if there's a major update and you want to see how the game is (I've done this before).
If you want to wait until the next update (which doesn't have an exact release date), you could play one of the other games.
I would recommend Pokémon Reborn, as it's more or less a base to understand how the other two games work and it's already complete, okay?
I hope I was able to help you. If you have any further questions, just let me know and I'll try to answer them as best I can.