Aurora = day dreaming and wishing for a relationship. Tiana = practical/continuously working and doesn't want love until it hits her directly over the head.

So yeah, these two are opposites in personality and activities. And also Aurora and Merida are complete opposites in activities and personality.

Same reasoning.

Tiana, Mulan, and Merida are completely opposite of Aurora. Aurora is dreamy and romantic, Tiana is realistic, practical, and doesn't need love. Mulan and Merida for activities, personality, and actions.

^But you don't have to be similiar to get along well with a person. I am very different from Rapunzel( not exact opposite but still rather dissimiliar to her than similiar: intolerant, tense, unfriendly, unpopular ) but I DO get along well with people like her in real life. Much better than with people who are similiar to me.

I don't think that Mulan would have problem with Aurora, despite them having major differences( leaving alone that I don't even consider them opposites). I don't even think that Mulan would dislike/disrespect/find annoying any of DPs(I think she would only unpleasantly surprised by Merida's cake story but still wouldn't hate Merida), she seems very tolerant and peaceful person to me.

I pick Tiana not only because she is different from Aurora but also because Tiana is irritable, argumentative, judgemental and somewhat even arrogant. She is not a kind of person who easily accepts the opinions that are different from her.

Tiana is at least poised like Aurora. Merida is total opposite in terms of looks, personna and value system.