Asking, Lobbying, or threatening reports on players (report X for...., We will report X if you report Y...., Do X or we will report you....) all counts under escalating punishment, Riot has stated it falls under "harrassment" and is a punishable offence.
Riots do not stack (the 9x report myth), and riots are supposed to be done in SILENCE.
Begging, lobbying, or trying to coerce other players to "Report X" is seen as Dogpiling, starting a witchhunt against another player.
So best not to do it.
If I see people lobbying for reports, and begging "Report X..." I generally report that person, NOT the target they are trying to dogpile me onto"
If its blatent enough, both teams will see it and agree, But its not your job to dogpile onto other players.
1 report = 9 reports,
Do it in silence.