Infernape - Looks good, you might try Life Orb isntead of Focus Sash, but it's not really required. You might consider Close Combat over Mach Punch, and Flare Blitz over Fire Punch (which would make him hit insanely hard), but that would make him kind of suicidal, your choice. Also if you do go with F-Blitz and C-Combat, you will probably want Blaze instead of Iron Fist, and a different item. However, your set is fine, and you don't need to do anything to it.
Gengar - Your set is OK, but I would suggest replacing Icy Wind for Taunt, and replace Thunderbolt for Destiny Bond. Focus Blast and Shadow Ball have good coverage, and Taunt lets you stop walls/stallers/set-up sweepers. Once you taunt the enemy you can either Destiny Bond if you think you are going to faint, or you can go attack the enemy. If you want something a bit less suicidal, you could go with Giga Drain instead of Taunt, amking yourslef more of an attacker with the capability of taking your enemy down with you. And for some reason not many people predict destiny bond.
Tyranitar - He needs work. Your set isn't terrible, but it is outclassed by this set from smogon:
EVs: 4 HP, 252 atk, 252 spd
Ability: Sand Stream
Fire Punch/Aqua Tail/Ice Punch
Merely the fact that Tyranitar had Dragon Dance in its repertoire allowed it to see some use last generation. However, with the advent of Black and White, it is much less common, which is perhaps, if anything, a boon to this set, making it more unpredictable. Dragon Dance resolves the problem of Tyranitar's middling Speed, allowing it to outspeed a variety of threats including Starmie and Latios after a boost. From there, the bonus to Attack is all but overkill; many teams just may struggle to find an answer to +1/+1 Tyranitar. The two STAB moves are obvious choices, but the last moveslot contains a variety of options. Fire Punch allows Tyranitar to nail Ferrothorn and Scizor. Scizor should be hit while it attempts to switch in, however, as it could otherwise pose a threat with Bullet Punch. Aqua Tail grants you a reliable way of touching Tyranitar, Gliscor, and Hippowdon, while Ice Punch delivers a much more commendable dent to Landorus and Gliscor.
Notes: In the set, they gave a Choice between the Lum Berry, the Air Balloon, and the Life Orb. I chose the Air Balloon for yo because I fugured it would take the edge off of your teams Ground-type weakness.
Gliscor - If you want an offensive Gliscor, Power Trick is not he way to go, but thank to smogon, I know what is:
EVs: 252 atk, 252 spd, 4 def.
Ability: Sand Veil
This set passes up the use of Gliscor's fantastic ability to wall a variety of dangerous threats, and instead acts as an excellent lure to many of its usual switch-ins. This set is derived from the one that was so popular in Little Cup for Gligar, and it shows great effectiveness in OU. This set can abuse Sand Veil to the fullest, allowing Gliscor to get up a Substitute with ease, before it can Swords Dance up and wreak havoc with its +2 Flying Gem boosted Acrobatics.
>The moves listed allow Gliscor to reach its maximum offensive potential. Substitute is used to great effect on this set, as when Gliscor first switches in, most opponents expect it use Protect to activate Toxic Orb. This Gliscor, however, can Substitute, and then Swords Dance up before wrecking the switch-in with an extremely powerful attack. Acrobatics, when boosted by a Flying Gem, can OHKO even Rotom-W, which resists the attack, after Stealth Rock. Sand Veil Garchomp has nothing on this.
Mamoswine - Your set is great, but there is on problem...the only thing mamoswine is doing for this team is murdeing the synergy. With Mamoswine in there, you have 2 pokemon weak to fighting, and 4, count 'em 4 pokemon weak to water. I strongly suggest Mamoswine gets the boot, and a new pokemon takes his place, that pokemon will be...the famous...the legendary...Politoed! Politoed's Water Absorb will easily let him switch in on a Water attack, get some recovery, and retaliate. So now you have 3 pokemon weak to water, and 1 that absolutely loves it! Smogon has the same st I was going to suggest, but their description was saying that Drizzle was the better ability for this set, but in this case it isn't, o I will be writig the description instead of quoting smogon.
EVs: 252 spd, 252 spatk, 4 spdef
Ability: Water Absorb (Smogon said Drizzle, but the situation calls for Water Absorb)
Hidden Power Grass
Hydro Pump is main STAB, and takes care of the Grond types that a some of your teammtes fear, and and Ice Beam and Focus Blast serve as coverage. HP Grass hits the Water types whose atacks you are switchin into, and the Scarf lets you actually be fast enough to hit them first.
Metagross - Looks good