GOUKI

The "Gouki" monsters seem to focus on a straightforward aggressive strategy, using effects to increase their ATKs or decrease the opponent's. The Main Deck monsters have 0 DEF, being immune to the effect of "Gouki The Great Ogre", who, in turn, has no DEF; that makes it so that they generally have an advantage over the ATK of opponent's monsters', since theirs' will likely end up reduced while yours' won't.

Additionally, the Main Deck "Gouki" monsters released up to Cybernetic Horizon all share this effect "If this card is sent from the field to the Graveyard: You can add 1 "Gouki" card from your Deck to your hand, except [itself]". This keeps you from losing unneeded card advantage upon using them as Synchro/Link Materials, or with cards like "Transmodify", "Downbeat", and "Spiritual Earth Art - Kurogane".

Gouki-Knightmare

When Gouki were first released, they were rather ignored in the competitive scene. The general consensus of top players was the Gouki Link Monsters were not strong enough or disruptive enough to compete with the top decks of late 2017 and early 2018, such as SPYRAL, Trickstars, and Pendulum Magicians, and there were not enough generic Link Monsters to make a non-Gouki Extra Deck. However, in Flames of Destruction the Knightmaremonsters were released, giving this deck a set of generic Link Monsters to utilise that could Extra Link and/or hand loop their opponent, providing a powerful end-goal for this deck to aim for going first. This strategy uses the card advantage generated by "Gouki"s in conjunction with "Isolde, Two Tales of the Noble Knights", "Knightmare Goblin", and most notably, "Firewall Dragon", to kick-start their plays. Once "Firewall" was Summoned, the player could repeatedly replenish their hand with "Gouki" monsters after the ones on the field were used as Link Material, and then immediately Special Summon those searched monsters, thus providing an extremely consistent stream of Link fodder for the "Knightmares" while losing little to no hand advantage in the process. Their usual end boards would consist of a combination of "Firewall Dragon", various co-linked "Knightmare" monsters protecting other co-linked monsters from various effects, "Tri-Gate Wizard", and "Topologic Gumblar Dragon", the last of which could use the hand advantage generated to force the opponent to discard up to 4 cards before they had a chance to make a play.

This deck proved to be the strongest Link Summon-based deck thus far seen in competitive play, with many other decks playing as many as 10 or more handtraps (the deck that won the 2018 World Championship played 16 in the 42-card Main Deck) just to try and stop this deck. Eventually, Knightmare Goblin and M-X-Saber Invoker were both banned to try and slow this deck's combos, and Called by the Grave was Semi-Limited to try and make handtraps more effective against it. It has continued to see competitive success since, but is perhaps no longer the best deck in the format.