Why not "c'est ennuyeux" ?
That would be it's boring. So yes, I guess you could use one for the other in many circumstances. It is not however a better translation. C'est épuisant would work as well
I think @Geoffrey878583 means "ennuyeux" in the meaning of "annoying" (not "boring"). Close but not 100% exact.
Is contraire masculine or feminine. Because according to google translate i think its feminine
Le contraire, masculine.