Anti-Estrogens, namely Aromitase Inhibitors while using some steroids are necessary if the steroid or steroids you are using happen to convert to estrogen. They stop the development of enlarged mammary glands in males, prevent lactation, inhibit bloat, and reduce sensitivity to prolactin and progesterone. Posy cycle therapy is a must for all steroids.
When using Testosterone or one of it's many esters, an aromitase inhibitor such as Anastrozole is recommended to prevent estrogen related side effects. PCT is needed in the form of Nolvadex and Clomid to stimulate natural production of testosterone, restore size and function to the testes, and to prevent side effects from estrogen from the shift in hormonal balance.
There is no way to work around it. You could run Testosterone without an Aromitase Inhibitor, some people get along fine, but why risk the moon face and bitch tits? It's a dice roll so it's best to prevent all this shit. You need PCT as well, otherwise you will lose all your gains and end up with less muscle than when you started. Without PCT, you will have a limp dick for months and feel fatigued and depressed.