Hy there...
Here is my decklist of a pure Mekk-knight deck. For the few people who never seen this archetype, this deck where released in 2018 and the gimmick of mekk-knight is to play with both player's collomn.
In fact, most of them have the effect that let you summon himself from hand as long as there is two cards on the same collomn on the field and you special summon the mekk-knight on this collomn, but you can only speciel summon one copy of each name per turn.
First of all, mekk-knight is meant to mostly goes second, because their sommun doesn't trigger negates, which is nice to break boards, on top of their high Atk and Def point, and their easy summon condition when going second, plus they are super consistent and fastly swarm the board with high stats monster.
This is the reason why I don't play any hand-trap on main except nibiru, because every hadtrap won't be effective 100% of the time while board breaker on going second will be pulled of more often. Plus, our format is mostly going first deck, so playing a going second deck gives an insane advatage because the result of the coin flip will basically never matter as you will go second 90% of the time. Plus, a nibiru on main can be super effective as some deck won't be expecting him on game one.
I play gameciel as a way to settup collomn for "blue sky" who can search from one to three mekk from your deck to your hand, and if this resolves, you will certainly otk your opponent.
Girsu is obviously a three of because it is a one-card iblee, which can setup your following up and your collomns easely. On top, I play corruptor Iblee because she will summon on the opponen't side of the field, so great for "blue sky" and enabe your opponen't for playing nibiru at all, and might shut down a lot of meta deck, mostly tri-brigade and swordsoul, who will struggles getting rid of her and not focuses on your board. But becareful of anaconda verte predaplant, you might end of giving them a free access to dragoon or DPE (or battle buttler for prank-kids).
This deck is really good and have a lot of good matchups against meta decks, one of the easiest one is Sky Striker, mostly thanks to your mekk-knights being able to swarm the field, and also some card are a huge counter to them, just like iblee, gameciel world legacy's whispers, a trap that negate spells on field that is on the same collomn of a mekk-knight (this is not a trigger effet and can even prevent any dodging).
To be honest, there is no budget option for pot of prosperity, this card is unfortunately mandatory, especially since pot of desire, the only card that where not bad enought to see a little bit played, but now, prosperity is a must-play.
I play gameciel because the bird lock isn't releavant anymore, since simogh got hit, and I don't see any deck running a barrier statue to normal nummon and pass... I would also recommand you to change the evenly matched for lightning storm if you can afford it, but I can't so I have to play some "budget" option instead, that doesn't really synergise with the deck and make you loose your deck advantage by making you loose your battle phase.
I know there is a lot of people who want to play "World Legacy World Armor" and "World Legacy succession", but I found out thatthe WLWA combo is like putting all your eggs on the same basket, and I prefer keeping more board presence to be able to control my opponent easier. Also, by playing the deck a lot, I've found out that succession is an amazing card but isn't needed on mekk-knight, because usually, you will rapidly win or rapidly loose, and I have never used this card. This is the reason why I play a one-of called by, who can prevent an ash on Blue or, more deadly, A droll and lock bird.
For the side deck, there is a lot of heavy backrow trategy, so I had to play tree of twin twister on top of the two cyclone to get rid of the skill drain and ice dragon's prison to banish the two Eldlich, which means game for us. Also, putting a contact "C" might proove fatal against sky striker or prank-kids and swordsoul and many other decks. Lancea is great because it make passes turn any flowandereese deck and handicaps phantom knight (in the condition that they haven't they adventurer negate). Red reboot is just another backrow-hate.
This deck might seems like nothing but from now, if you still play two cards on the same collomn, karma will send you a mekk-knight deck and you will learn why you have to NEVER play two cards on the same collomn.
A pretty fun deck with a lot of potential, each duel is for me like a boss fight, where I have to give everything I have to break the opponen't board and setup a little bit of control, who can prove fatal if they don't have enough cards to come bach.