look you don't have to ever stack steroids with testosterone.. the whole 'test should be your base' is a myth
guys in the old days shied away from testosterone cause AI's didn't exist in those days.. they knew to avoid it cuz they didn't want bitch tits.
now having said that testosterone should be treated as an androgen.. and with that it will enhance your cycles which involve an anabolic already. example would be test stacks well with tbol, var, primo, masteron, etc.
however when you already have a strong androgen like tren, stacking testosterone is actually not the best idea. you should stack an anabolic with tren for best results and least sides. i always stack primo, tbol, var with my tren for outstanding results