I'm not sure, I think maybe John Smith because they're both sailors and adventurers.

To put my thoughts in one comment: I think that Eugene would despise Naveen, because he would remind him of the worst character traits if his Flynn identity. But I'm sure, he and Phillip would go along great, both mischievous, both a little rebellious, both ready to give up everything for the woman they love. And I'm sure, Maxumus and Samson would go along well, too.
Naveen on the other hand would go along great with Aladdin - they are both the most childish princess out of this lot.
Shang and John Smith are both soldiers and leaders in times of war. Since Shang is a little bit more reserved, it might look like an odd pair, but they have a lot to connect over.
Since I think that the beast isn't really the outdoor type and has a very aristrocratic upbringing, Charming might be a good fit for him.
And romantic Eric naturally would like the romantic Prince....

They're sailors.