ScarfRachi's Vengeance

In a metagame where Genesect rules as tyrant, many fall to its powers. However, the beast from 4th gen has risen from the ashes to destroy Genesect. His name? Scarf Rachi.
Yeah, I'd make it all fancy and stuff but I don't know how to do that. Anyways, on with the team.

Jirachi @ Choice Scarf
Ability: Serene Grace
EVs: 252 Spd / 252 Atk / 4 SDef
Jolly Nature
- U-turn
- Fire Punch
- Ice Punch
- Iron Head

Oh boy. This guy is great. This thing is the ultimate troll against Genesect, outspeeding it by a measly one point (if both have scarfs). And since Genesect is dominating the early metagame, ScarfRachi is the perfect counter. U-turn is to keep momentum going. Fire and Ice punch provide coverage against Dragons, Ferrothorn, and Genesect. Iron Head is the obligatory STAB.

Terrakion @ Choice Band
Ability: Justified
EVs: 252 Spd / 252 Atk / 4 SDef
Jolly Nature
- Close Combat
- Stone Edge
- X-Scissor
- Earthquake

I really shouldn't have much to say about Terrakion. He's the hard hitter of the team. Slap a choice band on this thing and it's ready to go. Most of the moves on here are an obvious choice. EQ is to deal with annoying Aegislashes thinking they can switch in on a CC.

Landorus (M) @ Life Orb
Ability: Sheer Force
EVs: 252 Spd / 252 SAtk / 4 HP
Modest Nature
- Earth Power
- Focus Blast
- Psychic
- Rock Polish

Why not add even more overpowered beasts to this team? Landorus is a really good special attacker, due to Sheer Force. I run modest nature over timid because of extra power; however, a timid nature is also fine. Earth Power and Focus Blast are obvious moves for this set. I run Psychic over Hidden Power Ice because Hidden Power got a nerf of 10 power this gen. Rock Polish is to get a boost and guarantee a late-game sweep. While this set is walled by dragonite, I can usually manage it.

Charizard @ Charizardite Y
Ability: Blaze
EVs: 252 Spd / 252 SAtk / 4 HP
Timid Nature
IVs: 30 Atk / 30 SAtk / 30 Spd
- Fire Blast
- Air Slash
- Solar Beam
- Roost

I'd take Charizard Y over X any day. This thing has an enormous special attack stat when mega evolved, and with combined with drought, and cause some huge damage. Fire Blast is to destroy anything that doesn't resist it or immune to it. Air Slash is for obvious extra coverage. Solar Beam is to hit bulky water types very hard. Bulky Rotom cannot switch into this at all, since it will be 2hkod. Scarf Variants have a chance to be ohkod after stealth rocks. Heatran is the only complete stop I can think of at the top of my head. Roost is to provide healing, as Mega Evolutions obviously cannot have leftovers. It could also be used to regenerate damage taken by stealth rock if it comes to that.

Excadrill @ Leftovers
Ability: Mold Breaker
EVs: 63 Spd / 252 Atk / 189 HP
Adamant Nature
- Earthquake
- Stealth Rock
- Rapid Spin
- Rock Slide

Honestly, this guy is just for Stealth Rock and Rapid Spin support, mainly for Charizard. This moveset is self-explanatory. I plan on replacing this with Donphan and see how it works. But for now, Excadrill stays.

Suicune @ Leftovers
Ability: Pressure
EVs: 252 Def / 252 HP / 4 SAtk
Bold Nature
- Calm Mind
- Rest
- Scald
- Sleep Talk

Ah, CroCune. Such an underrated set. This thing has amazing bulk, especially when couple with calm mind. This thing can pull off a sweep easily if its counters are gone. Calm Mind is to boost Suicune's already great bulky and usable special attack stat even higher. Rest and Sleep talk are obvious. Scald is chosen over surf because of the burn chance it can get on powerful physical set.

So that's my first RMT! Thanks for reading and I hope you give comments on how I can improve this team any further. See ya later!

Hm... Looks pretty good. Only a few comments...
Firstly, this seems like a team very centered around Jirachi and Zard Y, with very common Pokemon to cover weaknesses, which is never a bad thing, but there seems to be a few issues. Alot of your pokemon share common weaknesses. Excadrill, Landorus, and Terrakion all have a very ugly water weakness that they share, and a lower-end special defense stat. They all seem like perfect targets for a Scarfmie or Greninja. Especially since Greninja will outspeed all and Starmie can resist Close Combat. I would probably drop Excadrill, but not for donphan. If you really need a rapid spinner, I'd consider one with higher Special defense, because other than Suicune, you are lacking a bit of it. Realistically however, I would enjoy the idea of espeon on this team. Less people set up rocks this generation, and espeon can be a good support pokemon. That magic bounce and dual screens ruin almost any stealth rock setter with the exception of T-Tar and Krookodile, and its always nice to have magic bounce for those damn klefkis and sableyes.
Personally, I hate Rachi for haxxy troll reasons, but I'll give you that he is best genesect counter, and looks very viable.
Another opinion, I much prefer Zard X over Zard Y. Sorry. But just like with Rachi, this is only personal opinion, Your Zard Y set looks very effective.
I like the suicune, it gives you much-needed variety for this team. If you are going bulky setup sweeper with suicune, then Scald is definitely better than Surf, for burn chance.
I guess, in conclusion, this is a very nice team, but the trio of Terrakion, Landorus, and Excadrill on the same team leaves more to be wanted for it. If you want Landorus as a special sweeper (which is not a bad idea), and Terra for physical, then Excadrill is definitely the weak link. Anyway, just my opinion.

Thanks for the comment! I've played with this team a lot by now and I did notice that Greninja gave me some problems. I may indeed have to replace on of them for another Pokemon. The Espeon sounds really nice. Again, thanks for the reply!

Hope you don't mind if I give you some opinions about it.

Having a scarfed Jirachi is a huge threat, it can take down entire, unprepared teams, and if you ever have the wondrous luck of battling Fairy Monotypes (that are becoming increasingly more common), you can get some easy advantage by flinching them (if they survive), or inflicting one blow that'll pierce their already weak overall defenses.

Also, I have to agree that having a Bulky Suicune improves your chances of surviving great hits, and/or countering them back, as a phenomenal Special Sweeper, once it's been toughened up with some Calm Minds.

The rest of the team also boasts of a good offensive support, and a vital synergy that'll keep you alive, but my one and only change is to make Excadrill slightly more agressive, probably, maxing its Speed, and throwing in a Life Orb, to inflict great damage, and to keep your team weaknesses away.

Aside from how I'd play it personally, it's a great team!