Say I just to a little bit of exercise (enough to have some gain), what would be the supplements I should take to maximize gain and minimize pain.
I would think Creatine, Glutamine and ALC - Acetyl L-Carnitine.
What about fish oil?
What you want does not exist. If you understand the basics of nutrition, you need a certain amount of protein, carbs and fat in your diet. Beyond that, vitamins and minerals. That's just for living, so how about building muscle?
Bottom line: if you want to build muscle you have to work hard and lift heavy things. Your body will adapt to the stresses you put on it (exercise), and in its recovery it will supercompensate to handle what you told it to do plus a little spare capacity. If you want to build muscle you have to repeatedly increase what you ask of your muscle.
If you take protein supplements, creatine, l-glutamine, etc. without putting in the work that causes your body to build muscle, they will be going to waste. Anything your body does not need is excess, and all excess is either discarded (as waste product) or stored as fat.
In short, no pain, no gain.
Additional information about the specific supplements you listed:
If your training stimulus is mild, the inflammation induced by the training is well within the body's normal means of recovery. Additionally, if you have a healthy diet you'll receive all the Creatine, Omega 3s, Glutamine, and ALC your body needs to function properly.
However, if you are pushing yourself as an athlete training for their sport does your needs for these items can outpace your ability to eat the food that contains them. By this I mean you are exercising several times a week at high intensities for the purpose of getting better, stronger, and faster at your chosen sport. I am not talking about Zumba or Yoga classes (while they are challenging disciplines, they don't have the same recovery requirements as someone training as part of a basketball team).
Don't waste your money. If you aren't willing to put in 'more than a little' exercise, the impact you'll see from the supplements will be slim to none. If someone told you that you looked bigger while you were taking creatine, that's because creatine causes you to retain slightly more water - so you had a bit more water weight bulking you out, but that's not the same as actual muscle gain.