To pulse or not to pulse...that is the question. The answer tends to be very dependant on the steroid you are intending to pulse.
Bad Idea: A bad choice is typically any steroid that will cause HTPA suppression too quickly. These puppies will cause shutdown very quickly, and there is a good chance your off days will be spent in attempt to recover androgen levels.
Base Injection: Base injection refers to injecting a steroid without an ester attached to it such as Test Base or Tren Base.
Transdermal Steroids: Believe it or not, transdermals will likely shut you down the hardest out of all of these. Reason being that with an injection or oral steroid, you create a 'spike' in hormone levels. Once the serum levels peak, your body can start to recover. When using a transdermal base, there is no peak: serum levels hit a point and stay fairly constant for a prolonged period of time. This allots less time to recover and more time to continue shutting you down.
Methyltest: Very liver toxic. HTPA suppression comes very quickly with this as well.
Metribolone (Methyltren): This is the most toxic steroid in the history of steroids. This stuff makes M1T look like a can of 'alcohol-free' beer. Not only will it cause fast suppression, but liver toxicity will not be hindered enough to make it safe.
M1T (Methyl-1-Test)*:This will cause shutdown too quickly to be used for a pulsed cycle; however, it could be effectively pulsed to 'kick start' an injectable cycle if you want to use the anabolic effects of M1T and lessen the liver toxicity to a small degree.
Epistane: This is probably the best one to pulse (in thesinner's opinion). Reason being that it blocks ER's and aromatase in addition to it's anabolic effect. This causes your body to "think" you don't have any estrogen, and so it will create more endogeneous androgens (i.e. natural testosterone) in order to make up for this false deficit.
Methyl-4-Hydroxy-Nandrolone (M4OHN): This seems to be one of Dr. D's favorites. This is great because it's very mild, causes very little suppression, and very clean. Don't let the methyl confuse you, this is very light on liver values.
Dianabol (Methandrostenolone): This was the steroid from which the pulsing concept was born. Effective enough to give an anabolic effect without causing too much shutdown. It's ability to block glucurcortoid receptors helps against suppression.
Superdrol*: This is a great choice because it's effective enough to cause for gains, mild enough not to shut you down too hard, and dirty enough that pulsing will help minimize sides.
An important thing to note is what you are using. Not all superdrol clones were created equally. This compound is commonly synthesized from Oxymetholone, which is a nasty nasty little fella. It may not be wise to just get the cheapest clone you can find on this guy. Anabolic Xtreme's Superdrol and Genetic S.D have both been validated by Dr. D as being 'good' makes of the compound.