This has been around since Rumbles were introduced, however now there is now a stark inconsistency. Max Plunder Points for a Rumble Rival shows the 25% bonus amount but the max BP shown does NOT include the 25% bonus amount. Should be one or the other (probably should include the bonus amount).
[2.3.0] PH9 (less than 30PR) versus: PH8: 328PP, 11BP PH8 Rumble Rival: 410PP, 11BP PH9: 500PP, 15BP PH9 Rumble Rival: 625PP, 15BP The bonus BP is awarded if you win but not shown before the battle.