I think there is certainly a fundamental problem with your team. Typically HO team builders attempt to figure out what they want to be walled by (and therefore break down), and then build sweepers around that. Typically you want the dual-screener, 3-4 mons that wear down the counter, and then 1-2 mons that can force out the counter so that it has to eat sr damage again as it comes in next. I didn't see you discuss the intended targets, so I will assume you did not do that.
With that being said, your team is a bit walled by Rotom (which in my opinion should be the counter of focus for this team), but not in such a way that you can wear it down. With this in mind I recommend that you change some movesets to more effectively accomplish your goal. The first thing I will recommend is that you change your Machamp to Tyranitar. He has more Special bulk and nearly as much Physical bulk with only 4 HP invested. One of the major reasons I think this change is important is that Tyranitar gives you a way to force out Scarf Rotom and other Electric types, and the passive damage may seem a negative thing, but in actuality it helps you wear down counters much more easily.
The Tyranitar set I recommend is:
Tyranitar @ Babiri Berry/Leftovers/Lum Berry/Life Orb
4 HP / 252 Atk / 252 Spe
Jolly
Dragon Dance
Stone Edge
Crunch
Fire Punch / Earthquake
Tyranitar really hates that the metagame has decentralized away from Latias and Rotom, but he still gets good setup opportunities on Heatran, and he also enjoys Scizor's 5% drop in usage (although the Babiri Berry prevents it from being a counter)
The next Pokemon I would like to address is Metagross. Metagross has excellent synergy with Scizor and Gyarados, but you aren't using a set that will help you wear down Rotom. At the very least I would replace Explosion with Zen Headbutt, which allows you to hit Rotom fairly hard. The accuracy of Zen Headbutt is sometimes disappointing but it is better than being utterly walled when Rotom comes in. Most people put Thunderpunch in that slot, but Gyarados is the only thing you will be hitting substantially harder with Thunderpunch > Zen Headbutt. You could also stand to use a bit more speed on your Metagross. It takes 225 Speed (196 EVs) to beat Neutral Choice Scarf base 100s after an Agility (Neutral base 100s were uncommon when Mence was around, but are now becoming more popular), and you don't beat +Speed ones unless you go Jolly, so you can safely invest the extra 14 points into HP, meaning the spread is 60 HP / 252 Atk / 196 Spe Adamant.
For Scizor, I recommend using a bit more speed to help you beat opposing Metagross and Skarmory. I typically use the rather arbitrary 88 EVs, and then put 152 in HP (which reaches both a Life Orb and Stealth Rock number), and finally 12 in Defense. Keep the attack maxed out of course. Also I second the notion of putting Bug Bite > Quick Attack on Scizor. It is very useful for hitting Metagross, Swampert, and opposing Gyarados (which are 2hkod by Bug Bite + Bullet Punch in Sandstorm after Stealth Rock).
Regarding your Lucario set, I have a couple suggestions. First, the EV Spread. If you use a 29 HP IV and move the 4 EVs from HP to Special Defense or Defense, then you can get a Life Orb number. This is really only worth it if you use Life Orb more than 3 times, but I have often been in situations where I have been worn down so much that the extra HP I save in Life Orb recoil has saved me. I also noticed that you are using the Standard Lucario set with Crunch. I recommend that you at the very least test Bullet Punch, which not only gives Lucario more synergy with other teammates, but also eliminates common Lucario responses such as Scarf Tyranitar and Gengar. With the other changes I have made, it is a bit more okay that you are essentially hopeless against Rotom.
Hopefully you will give my suggestions a try, and good luck with your team. I always enjoyed theorizing with these teams. They are theory in motion.