You will get side drops from parties as usual. But those will only count towards the side story once you have transformed them.
To do that, you need to have an active RS, and both of you
need to have side drops from parties.
And then you need to attack the user ReelLoveSurvey - doing this will show your RS compatibility with emojis, both ways. The best compatibility emoji is

, and the worst is

. Good compatibility means a nice drop bonus, the more compatible the better. This is why a lot of people have been testing, to find their perfect match (perfect match is

both ways). This system is probably randomized like last year, so the only way to know your match is testing. I don't think stats matter too much.
Once you fight that profile, it will transform your drops and add the bonus accordingly.
Basically: collect drops from parties, have a RS who is also collecting, then fight ReelLoveSurvey and you'll progress on the side story.
I tried to explain at the best of my ability, sorry if it's still confusing!