Yea it's pretty unfortunate that there are no replays on cart, but one thing that might help is to take screenshots of both teams during the team preview phrase. After the match you can go back to the picture and review. It's nice since there definitely have been times when I've run out of time while thinking and will rush/make a panic choice (which usually ends up being 'okay Mimikyu in the back' lol). After the game I get to review it in more depth, which means the next time a similar situation comes up (which is a lot since at some point on ladder all these teams blend together), I can run through the whole process much more quickly. Even if you do have a linear team that wants to follow a plan of Pokemon A -> Pokemon B -> Pokemon C, chances are your team has another mode and being able to recognize when your initial plan might not work and you have to pivot to Plan B or C is a useful skill to develop as well.I also think my flaws are in playstyle > team structure. It would help that I could save replays of my losses so I could watch them once in a while and learn from it.
This process does indirectly improve your play since choosing the correct Pokemon and/or getting a favorable lead matchup makes the game go a lot smoother. Also fortunately stall does not really exist so most matches are not too long and I find I can remember most of the turns. Taking these screenshots can help you de-tilt and dissuade you from spamming ladder and getting caught in a downward spiral since you need to take the time to review before you queue up for the next match.
Try not to get too discouraged if you feel you are playing badly or feel you are getting outplayed by the opponent a lot. Sometimes you just need to experience things before you adapt to it and that's fine since there are not many unique ways to win this Gen so eventually you'll learn to adapt to these strategies. Or maybe you ran out of time to perform a calc but you were able to do it postgame and that new bit of information can improve your future play. Hope this helps and good luck!