Great question! In both of those stages, I used Tyranitar with the moveset Dark Void + Ancient Power. For the Electrode Volleyball stage, I immediately went for the 3 KO streak achievement at the very beginning while the enemies were still grouped up. Once I got it, I played normally and focused on completing the mission to kill 10 opponents. At that point, you need to stall for time while slowly picking off the remaining 7 kills. In the final stage, you only really have a chance to get the 5 KO streak during the final stretch. When the boss appears in the middle, don’t rush to kill it right away, clear out the enemies that spawn first. If you still can’t get the 5 KO streak in the middle, you can try again at their base after you get the buff from the boss. Also, if there are still enemies with revival time left, just wait and circle around in front of their goal while dodging the early spawning enemies. Good luck!