The best part about this deck is it's amazing search power and the synergy of effects with each other, with Gravekeeper's Recruiter as your main search engine. Baggy Sleeves is great because it further increases your card advantage whenever a high leveled monster you control is destroyed.
When Gravekeeper's Recruiter is sent from field to graveyard, you can search any Gravekeeper monster from your deck and add it to hand. This effect is really good as Gravekeeper's Recruiter only needs to be sent to the graveyard not destroyed meaning you can use him as tribute to get his effect out.
Starting with Gravekeeper's Recruiter is often better. Gravekeeper's Recruiter can be tributed in many ways to help you use your search. One of the best ways is to use Enemy Controller to tribute your Gravekeeper's Recruiter and take control of your opponent's monster and search Gravekeeper's Chief then tribute summon him as well as reviving the Gravekeeper's Recruiter. You can choose which effect to use when you tribute summon Gravekeeper's Oracle using Gravekeeper monsters. It's almost always safer to lower your opponent's attack and defense since it weakens them and makes your other monsters able to take them down without the threat of a Mirror Wall, but destroying their set monsters can be good too to prevent flip effects if you are certain you can take down their face-up monsters. Increasing his attack effect is very situational and almost never recommended.
The deck that they are showing you is out dated. I got to Kog on 6/11/2017 with GKs
The cards are:
3x Angmarl the Fiendish
1x Mecha Phantom Beast Hamstrat
1x Gravekeepers Oracle
2x Gravekeepers Chief
3x Gravekeepers Recruiter
3x Soul Exchange
3x Ememy Controller
2x Floodgate Trap Hole
2x Xing Zhen Hu
Before you worry about GK decks, I urgently need to point out first that your grammar is still NOT competitive enough. Before you plan anything as well, consider trading your phone or your DL account to get some extra money, then proceed to learn grammar better. This will surely keep you more competitive than those craps you are blabbering above.