So starting off with the core of Victini and Terrakion, I realized that they pressure passive, bulky water types and ground types to switch-in. I then put on Manaphy to take advantage of the situations Victini and Terrakion are likely to create. Normally you do not want to build offense with the mindset of "Latios switches into Keldeo, so I'm going to put on Weavile because it beats Latios. Not only that, but Keldeo beats Scizor for Weavile". This is a flawed mindset to have because while yes, they do beat each other's counters and checks, they are not really exerting any pressure upon them. However, this is different in the case of set-up mons like Manaphy because it can actually punish the opposing team for bringing in their ground and water types against Terrakion or Victini by setting up with Tail Glow. Manaphy instantly becomes a threat, especially to slower, defensive teams. After adding on Manaphy, The team appeared weak to Garchomp, Excadrill, Mega Charizard X, Mega Pinsir, Mega Manectric, etc. while also lacking speed. To remedy this, I decided to add on a standard Choice Scarf Landorus-T. At this point, the team was pressured by Azumarill, Latios, Keldeo, and fairy types; in addition, I had not chosen a mega evolution for the team yet. Mega Metagross seemed to fit best in this slot because not only did it patch up the team's weaknesses, but it also had good offensive synergy with Victini, Terrakion, and Landorus-T because they all share similar checks and counters that can be pressured by each one of them, allowing one of them to clean up at the endgame. However, the team was still a little weak to water types even though they were pressured by the four aforementioned mons because not much was stopping them from spamming their water moves. Besides this fact, the team was still a little slow without priority, and needed something in addition for Bisharp. Toxicroak seemed a really good fit here because it really discourages the spamming of water moves, added priority to the team in Sucker Punch, and provided another Bisharp Check.