YOU SAID:

I ain't ever seen 2 pretty best friends, its always one of them gotta be ugly

INTO JAPANESE

私は2人のかなり親友を見たことがありません、その常にそのうちの1人は醜い必要があります

BACK INTO ENGLISH

I've never seen two pretty best friends, one of which should always be ugly

INTO JAPANESE

私は2人のかわいい親友を見たことがない、そのうちの1人は常に醜いはずだ

BACK INTO ENGLISH

I've never seen two cute best friends, one of them should always be ugly

INTO JAPANESE

私は2人のかわいい親友を見たことがない、そのうちの1人は常に醜いはずです

BACK INTO ENGLISH

I've never seen two cute best friends, one of them should always be ugly