The only drug I was aware of that "helped" pool players, were "Uppers" or Amphetamines. In the old days, many hustlers used this stuff on a regular basis. I don't know how prevalent it's usage is today.
On uppers, you see better, feel stronger, and feel like you'll never miss a ball. A good player might not miss for hours on this shit. I mean you're totally zeroed in and fully focused on every shot. You see everything so clearly! And you can play a long, long time! When you finally come down, it is a hard crash. I imagine players here in the USA are still using them to a certain extent, especially the road men and full time gamblers.
Did I ever use them? Yes, once or twice. I used a little "white cross" a couple of times to stay awake when playing a long session. I don't even know for sure what they are, but they were around back then. I also tried some prescription "uppers", that my dad (a doctor) got for me. They were "black beauties", as Jimmy Reid liked to call them. I just didn't care for the after effects and didn't like the feeling of playing high, so I gave them up after a couple of experiments. I will say this, they worked! I could definitely play strong on them.
I remember guys used to gobble this stuff like candy. Ultimately they paid a price for using it. Like all drugs, it will take a toil on your body.
I remember the match where Frank Tullos beat Eddie Burton. They played all night. Frank played "on the natch" and Eddie was using every stimulant known to man. In the end Frank got there when Eddie began to come down from the pills. That night left an impression on me.