Since we have an ‘honor’ system that will likely very rarely be used in PVP and is pretty pointless to use in general, how about on the post-fight PVP screen we had a simply 
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. Each player would have an invisible tally, each is +1, each is -1, and each day the current tally is cut in half (this is to facilitate a score returning to 0 over time). The chances that the player is selected in PVP for combat is affected by their current tally.
For example, Bob builds an interesting team, not something meta. People that face it like the newness so give it , so it is more likely to show up as a choice for people, Bob gets more fights and more rewards for defending, so Bob gets rewarded for building a fun team.
Jim builds an easy team that gives event stones, same thing happens.
Scott decides to build a looping rope dart team that randomly never lets you make a second move. People give it a , Scott’s tally goes real negative, and he stops showing up as available opponents.
Randy builds a team of 4 Bombs. Some give it for being easy, others for being boring, it balances out and shows up at normal frequency.
Since one of the major complaints about PVP is the diversity (and by extension seeing the same random loopers constantly), this would give the player base a slight way to curate what is seen. If it gets to be abused, have the tally make a smaller influence and/or have the tally decay more quickly.