There are many problems with the team. I really don't know where to begin.
Lets start with Blaziken:
It stacks type with Terrakion and Reshiram. It is as frail as a chicken. It doesnt help with defensive synergy. It is hard to set up with it. Blaziken is a better sweeper than Reshiram - isn't Reshiram supposed to be the main sweeper? I would just get rid of it. Blaziken was chosen by a hasty vote anyway. Mtr mentioned that the team is weak to DD Rayquaza, Mewtwo and Darkrai, right? So, with Blaziken not in the team anymore, I would like to add Genesect as our newest member.
Genesect @ Choice Scarf
EVs: 252 Atk / 4 SAtk / 252 Spd
- Ice Beam
- Bug Buzz/Explosion(Preferrably Explosion).
Terrakion is the most consistent member. It always does its job. No changes needed here. An optional change could be Taunt>Substitute.(Substitute causes unneccessary health loss;we dont want that to happen to our Extremekiller check)
Arceus Water needs Ice Beam. Mono-Grass Coverage sucks. It makes you a sitting duck. The speed needs to be bumped up to 56 to outspeed modest Kyurem-W.
Xatu. Bad Ev Spread. 252 HP / 120 Def / 136 SDef @Careful Nature works better. The evs allow it to survive a Darkrai's Dark Pulse. This is useful if I muipredict with Genesect and U-turn to Xatu as Darkrai uses Dark Pulse. Xatu can come back later in the match to reflect hazards one more time. The current spread dies to Dialga's Draco Meteor. My ev spread allows it to survive a support Dialga's Draco Meteor.
There is a problem with the moveset. It can only attack with U-turn, correct? Should Xatu be faster than the pokemon(Groudon, Dialga, Ferro, Forry) that use hazards, they can keep spamming hazards against Xatu and wait for it to switch out. Example - Groudon can keep spamming Stealth Rock against Xatu and throw out random Earthquakes/Stone Edge. With some luck, it should be able to get Stealth Rock up. I am not exactly sure about how to fix this problem.
If we are reliant on weather, we should have a bulky weather inducer or an offensive one to hurt its common switch-ins which will help Reshiram to sweep later on. Groudon can't reliably come in on Thunder as special attacks do a large amount of damage to it. Why did we choose Paradancer Groudon? It does not work in practice. Paradancer Groudon is an outdated set. No speed creep *sigh*. Ho-Oh beats this easily. Loses vs Dialga leads. An offensive set with Toxic/Thunder Wave/Protect/Dragon Tail(for pokeon trying to set up) in the last slot does a better job. BTW no fire punch means that Ferrothorn ad Forretress get chances to set up hazards. This is turn puts pressure on Xatu. The opponent can also double switch to something that threatens Xatu.
Mild Nature needs to go. Naive is the better option. Life Orb recoil sucks. Flame Plate is the better option - no recoil, scarf bluff. BTW Outrage doesnt do anything. It is quite weak. A -2 Draco Meteor does nearly the same damage as Outrage. Stone edge is a better option to hit Ho-Oh which can otherwise be a huge problem.
Thats what the pokemon are like in actual battles. I am surprised that no one suggested Ho-Oh as a teammate. The team itself has several issues. For an offensive team, its not very offensive; the speed of the battles can often be sluggish. There was no way to beat the Giratina + Chansey +++teammates core even with a hundred double switches. Reshiram couldnt really get an oppurtunity to hurt Giratina as it kept on fleeing. Blaziken is the most useless member - I am surprised that people actually voted for it. After Reshiram died, Giratina would wall the team for all eternity. Roar is not an option on Blaziken as our team lack hazards. The team needs serious fixing. BTW dont suggest scarf Terrakion. Arceus will be able to sweep our team if that is done. I will add more about the team some other time.