Mod downgrade

Hi, I am trying to create a modd world in 1.12.2 since I would like to move to a series of mods that include the Pixelmon Generation mod available only for this version. Except that, I usually play minecraft moddato in 1.15.2 I would like to avoid a too violent downgrade, so I was looking for
1-a texture pack that can report the textures of the new versions in minecraft 1.12.2;
2-a simple and fast way to download the latest file for 1.12.2 released of the mods of which I already have a precise list;
3-a mod that can report the features of the new minecraft versions in 1.12.2; I want to specify that I am already aware of the future versions mod, but I have tried it and I find it missing many details and therefore I would like to know if there is another less known, but that does more or less the same thing.

Thanks and sorry for the bad english.