Does a male violate any halacha in the Torah by watching a ball game at a sports stadium?
Are there any Gedolim that oppose going?
Rav Moshe Feinstein in his Igros Moshe Chelek 8:4 YD :11 writes that going to theaters and stadiums do not fall into the prohibition of bechukoseihem lo tolechu. However, he writes that one is prohibited from attending due to moshev letzim, bitul Torah (eventually l'gamri), nivul peh (promiscuity). Rav Moshe is clear that it is a forbidden to attend such places.