This has been asked a million times. The best ansywer is: everything they can get their hands on or afford, year round. I'll cut and paste one of my old posts answer this question...
I'm sure it varies, and I've been fortunate enough to talked to a couple of pro's about what they use, but the most extreme case of abuse, was as follows. This is what he was one at the time, weighing 308 (off season) at 5'8". About 2.5 years ago.
Test, he didn't say what ester(s) 1000 mg ed (yes every day)
tren 200 mg ed
dbol 300 mg ed
proviron 100 mg ed
hgh 16 iu's ed
humalog 10 iu's X4 ed
igf-1 (don't remember the dose)
a-dex 2 mg ed
t3 50 mcg ed
clen 100 mcg ed
He has had serious kidney problems (and who knows what else) since I had the oportunity to speak with him. Which is not a surprise on 300 mg of dbol a day. By the way, he never placed in the top 5 at the Olympia, and I'm not naming his name.
Being a pro doesn't sound all that fun now, does it.
On the other hand, I met a nother pro with a very impressive physique, who used the following in the off season, and weighed a solid 260 (not fat or extremely bloated either). He swore that is is really what he bulks with in the off-season, even though alot of guys use much more.
800 mg of test cyp once a week
400 mg of deca once a week
100 mg of anadrol ed
50 mg of winstrol twice a week
6 iu's hgh 5 days on 2 off
1 mg a-dex ed
Its really all about genetics. 500 mg of test might give me 3 times the gains it gives you, and some other guy might gain twice the lbm I could on the same cycle.