Hi Juan, congrats on the high ladder peak! I'm going to admit that I like this team quite a lot already, as it looks quite solid even in its initial state. I do have a few suggested changes however, so I hope I'll be able to help you out!
Notable Problems
In terms of offensive threats, opposing Jolteon variants that carry HP Grass can be somewhat troublesome. Swampert obviously won't be able to switch in safely, and every single member of your team takes significant damage from a LO Thunderbolt. Due to its extremely high speed stat, the only thing on your team that can actually outspeed it is Jirachi. Unfortunately, Jolteon is resistant to its STAB Iron Head, meaning you won't be able to KO it in some situations even with the extra flinch rate.
I think that you've got most offensive teams fairly well-covered, but Stall is a bit more of problematic. Despite the fact that some people some to think of Machamp as a stallbreaker, common Pokemon such as RestTalk Gyarados can or bulkier Rotom sets can switch into it without much of a problem. The rest of your team is very vulnerable to stall hazards such as phazing and entry hazard stacking; for example, Toxic Spikes severely limits the capabilities of Celebi, Swampert, and Machamp. Probably the only member of your team that does a good job of combating stall is SubSplit Gengar, but it shouldn't be relied on too much due to its frailty.
Suggestions
The Heatran set that you're currently running can be excellent with proper support, but it's out of place on this team without access to entry hazards (it works best with Toxic Spikes). I've read suggestions of other sets such as RestTalk, but that variant of Heatran really should be used with Spikes support to give it something to abuse with Roar. Since your team is more offensively-based, I'd recommend using a Taunt LO Heatran in its place:
Heatran (M) @ Life Orb
Trait: Flash Fire
EVs: 4 HP/252 Spe/252 SpA
Timid Nature (+Spe, -Atk)
- Earth Power
- Fire Blast
- Hidden Power Grass
- Taunt
This Heatran is great against just about any kind of opposing team. Offensive Pokemon will be hit hard by Heatran's strong Life Orbed attacks, while Stall teams have difficulty playing around it due to Taunt. Hidden Power Grass is a preferred option here for the ability to hit Swampert or incoming Water-types on the switch.
Other than that, most of the other team members seem just about fine the way they are. However, I would like to suggest a couple of minor changes to Jirachi's moveset. Trick is arguably the better option to use over U-Turn, as it allows you to cripple stall and any stat-uppers that you have trouble with. Zen Headbutt should also be replaced with Fire Punch, as this will give you a much better way to check opposing SD Lucario. Also, definitely switch to a Jolly instead of Adamant nature. Scarf Jirachi really needs max speed to help it function best, so Jolly is always the superior option.
Good luck with your team!