Stadiums have an effect on the entire battle feild until another one is played! Stadiums usually have their one effect such as all pokemon have no weaknesses or resistances (Which is really annoying when you just want to 1-shot) it will stay in effect until another stadium card is placed. Since you can only have one in use until you or your opponent places another it will make playing much harder or easier depending on the card!
A training center stadium
