I'm lazy so I'll just write a brief description of my thoughts on each Pokemon, then some overall concerns
Coffagrigus: main problem is, it's basically Taunt bait. While it can be annoying, that's pretty much all it can be, and simply switching around can completely nullifiy its ability to accomplish anything.
Gears: still basically helpless against ferrothorn, and lacks raw power to KO common Pokemon even with +1. also, i think Lum would be better than Chesto, can nullify a random freeze or burn while you set up if you can't afford to spend a turn resting.
Gengar: Red Card is pretty weak on a frail Pokemon like Gengar, against stronger attacks you'll get flat out 1HKO'ed, and even otherwise, your opponent could be switched into a Pokemon that bears an unfavorable matchup for you. Sludge Bomb is pretty suspect considering you have a very reliable STAB neutral coverage move in Shadow Ball, and you could easily use the slot for a better coverage move, such as Tbolt, HP Fire or Ice, Focus Blast, even Substitute.
Cradily: While the moves are individually fine, Ingrain locks you in without any out, making you incredibly vulnerable to Toxic, which would be fine on most Cradilies, except you conveniently leave out Rest. Your Rock/Grass attacking combination also leaves you prone to being stalled by physical walls such as Ferro, Skarm, etc., especially considering Stone Edge's PP will easily run out and is prone to miss. Even Burn will cripple you, negating your end of turn healing and shutting down your offensive ability.
Genesect: Pretty much ok, though using Lum really lowers your offensive ability, as you miss out on an item such as Life Orb to boost it. And, as people find out with Evire, Super Effective =/= 1HKO, and you can easily miss out on kills. Still acceptable by any means.
Omastar: I really detest the use of Focus Sash considering you have no spinner, and Omastar doesn't even Fly, so any Stealth Rock, or variety of Spikes basically renders you itemless.
As a whole: Your team seems pretty darn weak to set up sweepers, with some hazards and say, a Dragon Dance, Pokemon like Salamence or Dragonite can simply sweep through your team; the only problematic wall you have is Coffagrigus, who seems meant to suicide early anyways. Addressing that issue, if your opponent has an answer to switch in whatever you bring in after using Memento, you basically just wasted it. With all Pokemon ground limited except Gengar and no spinner, Spikes and Stealth Rock can rip through you, as by simply forcing you to switch around your team gets worn down quickly, also with Whirlwind, Roar, or Dragon Tail. You on the other hand, have no such hazards to wear down your opponent as the game wears down. This more so circulates to my earlier concern about sweepers,late game 1 turn of setup can mean gg