If having rot problems with cactus i can recommend clay pots.
Don't use the painted ones, just untreated clay.
The water evaporates through the clay and make the roots a bit dryer and it works really well for me.
I have had rot problems before but when switching to clay pots it is a problem of the past.
Plastic pots don't let any moisture out and no air in, these are best used for plants who can tolerate a bit more wet roots.
Edit:
Sometimes a layer of stones or other decorative stuff on top of the soil in the pots also becomes trouble.
If problem with rot, remove the dressing layer if you have one so the water can evaporate faster.
Good luck with your plants.
Grower
Growing active and sacred plants and mushrooms is fun.
Chemistry and technology is fun.
Anger, violence and restricting rules are NO fun...