Same feeling about Magic. I solve it by not playing for a few years, then jumping right back in. I just bought some Oddyssey block cards to finish an old block-themed deck, and I plan on keeping it. Same with my Tempest deck.
And Pokémon is brilliant as a game. It was a game long before it became a franchise. It just works. It's simple to get into, hard to get to the top. If you get bored, there's millions of other stuff to do. It's like a story-based sandbox game in many aspects. It's also a collector's game, which helps making it addictive. The idea of having to look for friends that play for those last final pokémon is brilliant too, and not many other games managed to pull it off in the same way.
I do agree that it gets a little stale if you played all of them and they keep adding more pokémon. Some are cool, like Slakoth/Vigoroth/Slaking, others are really lame, like Bidoof here, or that green starter pokémon that evolves into Meganium (compared to the awesome Venusaur).
I loved Fire Red/Leaf Green. The old formula with the awesome GBA graphics (I love the candy coating)