I'm here to suggest a "save" feature for Pixelmon, that I hope can be added at some point. But before I do, let me describe a situation: You're playing modded minecraft 1.12.2, you have plenty of mods installed including pixelmon, and one of those mods causes your game to crash. You reload the game to find the last several minutes of Pixelmon reverted.
The first part of the situation above is a pretty common occurrence with mods, but Pixelmon has a problem when it comes to crashes, and most of the time Pixelmon isn't even causing the crash, yet is affected by it. Pixelmon tends to revert the last several (unknown how much time could be lost) minutes progress you've made after a crash. Do not mistake this for reverting game progress as usually Minecraft autosaves quickly enough to only lose a few seconds of progress, I believe pixelmon uses a separate autosave feature for the actual Pokémon data of a player.
That's why I'm suggesting a "Save" button, something you can click if you're expecting a game crash
It's a very simple suggestion, but I'm hoping it could be added as a safety measure for us who play exclusively Single player, the button could be implemented in any way, the easiest I think would be as a keybind in-game, a more effortful version would be a button in the ESC menu, either way I think it's important to have this feature available for the reasons I've highlighted, a lot of crashes, a lot of situations where you know a crash is coming, etc. Or even if you don't know a crash is coming, you could save shortly after doing something (like organizing all your boxes) to save your progress even if it does crash.
I hope you, the Pixelmon team, will consider this feature for future updates of the mod.