....ok, so this isn't obviously going to be that good, especially with no Trinity. Unlike in Edison a Monster Mash deck is significantly harder to do just due to the insanely good spells and traps you are inhertently missing out in. The point of Monster Mash is that you ONLY play monsters, so obviously Chaos is the best archetype to go though. This is my most conservative attempt at making it at least semi-playable, playing it safe if you will.
One great thing about this deck is the sheer amount of plays here: you have tons of draw power, big monster potential, tons of recruiters, etc etc. Monster Mash means you will always draw a hand of good to great monsters while your opponent will draw maybe a few with spells and traps.
So.....how do we deal with that? Mirage Dragon helps a ton, as does the usual destruction you'd expect from a Chaos deck. You have so much to use here that backrow will usually not be enough to hold back all of it, especially combined with endless recruiter spam + eventual Chaos staples getting rid of cards, controlling the field, etc. Consistency is easy with the deck....well about as much without any spells, anyway. Everything draws or establishes advantage in different manners. Even silly stuff like the one Stein can go into shutdown or aid with aggressive pushes well. Maruading Captain helps cheat out out plays. Zombie engine is still one of the best plays even with no spells or recovery so it was a no brainer to stick on as well.
Jars are AMAZING in this deck. Unlike in conventional decks where this would hurt if you were saving up a certain spell or trap when it pops, it means nothing to you here, just a reason to fill up the Grave with Chaos fodder and stuff you don't need. Cyber Jar gives you a entire field to play around with while your opponent will at best get 2/3. Protector + Jars is a cool combo as well if you can pull it off.
Flip effects keep your opponent on your toes and will probably waste Noblemen given the sheer volume of recruiter fodder mixed in.
Side deck is mostly if you need to push more aggressively. Theban is weird, but having a 3000 beatstick is worth it for the quality this deck has. Magician combo is more consistency and you can work Creator tech if you need to recycle monsters + get more LIGHT monsters for Chaos. I'll be tinkering around with Mash more with variations (Megarock maybe???) which may or may not be better. It's a step to something, at least.