***for those not wanting to read the full thing here's the actual question: What do you/competitive players do with older cards that you're not allowed to use in the format?***
I've only been playing the tcg "extremely casually" because there's one issue I have with competitive play (which also makes up the 'normal' casual play).
This issue also made it so that I don't really invest a lot of time in the game either. The casual play used to be rarely and just me with a friend or two. I only made a full custom deck where I actually put some effort into with diamond and pearl. Ever since then I only made little changes to that deck up until the point where I wasn't allowed to play it anymore by the competitive format rules. After that happened (even tho I didn't play competitively at all) I pretty much stopped playing. Restarted a while later at the end of the plasma/b&w sets just because they suddenly brought it into our local tcg shop. Again only played casually with a small group. Every time I want to put effort into it because I find something I like, I get slapped in the face by the "format legal sets". I don't feel like putting a lot of effort into a deck (or the game in general) if I won't be allowed to use it after a certain time. When it comes to any tcg I mostly get into one deck/clan/type/whatevs you want to call it and keep it at that, trying to improve that alongside newer/meta decks. While I've noticed that it mostly fails to keep up with the meta, it is mostly how I'm able to keep enjoying the game. Only when it gets to a point that it's completely unbalanced in comparison (new/meta being ridiculously better), is when I throw in the towel and either move to a new deck or quit the game in general.
I know that some might say, since I'm a casual player I shouldn't pay attention to those formats but when I go to locals, those players mostly don't want to play against decks that don't follow the format while they themselves do.
I've only been playing the tcg "extremely casually" because there's one issue I have with competitive play (which also makes up the 'normal' casual play).
This issue also made it so that I don't really invest a lot of time in the game either. The casual play used to be rarely and just me with a friend or two. I only made a full custom deck where I actually put some effort into with diamond and pearl. Ever since then I only made little changes to that deck up until the point where I wasn't allowed to play it anymore by the competitive format rules. After that happened (even tho I didn't play competitively at all) I pretty much stopped playing. Restarted a while later at the end of the plasma/b&w sets just because they suddenly brought it into our local tcg shop. Again only played casually with a small group. Every time I want to put effort into it because I find something I like, I get slapped in the face by the "format legal sets". I don't feel like putting a lot of effort into a deck (or the game in general) if I won't be allowed to use it after a certain time. When it comes to any tcg I mostly get into one deck/clan/type/whatevs you want to call it and keep it at that, trying to improve that alongside newer/meta decks. While I've noticed that it mostly fails to keep up with the meta, it is mostly how I'm able to keep enjoying the game. Only when it gets to a point that it's completely unbalanced in comparison (new/meta being ridiculously better), is when I throw in the towel and either move to a new deck or quit the game in general.
I know that some might say, since I'm a casual player I shouldn't pay attention to those formats but when I go to locals, those players mostly don't want to play against decks that don't follow the format while they themselves do.
There are a decent amount of European events, though some of them do require you to travel, which is very similar to the NA scene just that it's across country lines instead of state lines. All of the big events are scheduled far in advance so you have plenty of time to make travel arrangements. You can always ask here or at a local league, or on the official Pokémon.com website if you'd like to find more events in your area. I know there's a separate website for the Benelux area official Pokémon events, and there may be something similar for other regions/countries as well.