scoreboard.java

    @Listener
    public void onJoin(ClientConnectionEvent.Join event) {

        for (Player player: Sponge.getServer().getOnlinePlayers()) {
            Scoreboard scoreboard = Scoreboard.builder().build();
            Objective powerObjective = Objective.builder().name("other").displayName(Text.of("Power")).criterion(Criteria.DUMMY).build();
            scoreboard.addObjective(powerObjective);

            for (Player other: Sponge.getServer().getOnlinePlayers()) {
                if (other.getUniqueId() == player.getUniqueId()) {
                    continue;
                }
                
                powerObjective.getOrCreateScore(Text.of(player.getName())).setScore(/* Power amount here */ 12345);
                Team otherTeam = Team.builder().name(other.getName()).displayName(Text.of(other.getName())).prefix(Text.of(/* Relationship color here */ TextColors.RED)).build();
                otherTeam.addMember(other.getTeamRepresentation());
                
                scoreboard.registerTeam(otherTeam);
            }
            
            scoreboard.updateDisplaySlot(powerObjective, DisplaySlots.BELOW_NAME);
            player.setScoreboard(scoreboard);
        }
    }