It's not just about the steroid you use, it is also about the diet and the training.
You need to incorporate explosive training and less 'hypertrophy' style training in your regime, which I am sure you do.
couple this with controling your protein and carbohydrate intake, decrease your bodyfat, increase your and increase your muscle density.
At a healthy maintainable bodyfat percentage of around 6-8 percent, as you approach your maximum weight, you need readjust your protein and calorie intake to insure maintainance of your current weight.
Any other gains in strength from hear come from slowly remodeling slow-twitch muscle tissues into fast- twitch muscle, and through training your nervous system concurently.
As for what steroid you choise to use for these purposes, your options are only limited away from the steroid the cause heavy retention of water such as anadrol.
steroids that come to mind for use:
dianobol in low dossage
and many more I am sure
Bottom line is, steriods can cause weight gain and water retention, but you can control this using your intake of calories, and protein, and your training methods.