Citra (the 3DS emulator) has been progressing fairly nicely. The official builds now have things running from GPU, so most games can be run at great speed. I've dabbled with the emulator some in the past. Some of the unofficial builds allow using Gateway Cheats, but the official builds don't have that option it seems.

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Anyway, I've attempted a small table so far for Dragon Quest VIII 3DS EUR version that's available. I own a 3DS and have Dragon Quest VIII purchased also.
I believe I have something that is getting base pointers for either the Nightly or Canary builds. I tested it on both of the builds released today (March 16, 2018). They both pull in the correct pointers.
Options so far:
Infinite HP All Members Dragon Quest 8 3ds Casino

Infinite MP All Members
Infinite Bag Items
Dragon quest 8 3ds casino map

EXP Multiplier
Gold Multiplier
Walk/Run Speed Modifier
Multiple Moves Per Turn
Always Preemptive Attack
Always Critical Hit
Monsters Always Drop Item
512 Skill Points Remaining
Allocate Skill Points Without Limit of Level
Dragon

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Always Super High Tension
Pointers to Gold (Money), Casino Coins, Item Bag Slot 1 ID and Quantity, Hero HP, MP, Skill Points
While not many options to start, it's just a test to see if I can create a table that survives the Citra updates which are ongoing. I may attempt to add some more things later on. If any of you have particular requests, you can let me know. Some types of options are harder to make on emulator's, but I can try to do what I can. These older style games usually have static addresses once you get a base pointer. Enjoy!
EDIT 1:
I kind of figured out how Citra stores the memory and rewrote some portions of the table using LUA code that should survive updates fairly well. In the process, I figured out how to apply Gateway Cheats manually to the memory. I have Always Critical Hit that ymyn wrote for Gateway Cheat of Dragon Quest VIII. I have it applied with the CE option on official builds of Citra using the table here. I guess there is not much interest currently for this but it's here for anyone to try when they get the chance. ymyn did the majority of the Gateway Cheats, so much credit goes to him for the pointers and offsets to use. I just put it in CE format here.
EDIT 2:
I have converted some of ymyn's Gateway Cheat options for Dragon Quest VIII EUR over to this format for use in Citra. I added EXP Multiplier, Gold Multiplier, Always Preemptive Attack, Monsters Always Drop Item and Always Super High Tension. These options basically rewrite code once and they cannot be turned off once you turn them on without a restart of the game.
EDIT 3:
I fleshed out more options from both ymyn's remaining Gateway Cheats and some that I did. It's fairly complete with options I would consider using in my playthrough. I believe I have things working regardless of what version of Citra you are running, but let me know of issues. These options I believe might work on the USA version of Dragon Quest VIII, but that one is not readily found in format Citra needs. Anyway, Enjoy!
EDIT 4:
I added All Party Members Joined by request. It adds all members to your current party.
EDIT 4.5:
mac4500 requested some additional options. I added Run Through Monsters and (On Board) No Encounter.
EDIT 4.75:
mac4500 requested All Items. They are in this update.
EDIT 5:
Update for new Citra builds around June 28,2018. Citra changed how it stores the base memory address so it requires this update for later builds now.
EDIT 5.1:

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Fixed the issue with scripts for Citra builds after June 28, 2018. Please use CE 6.7 instead of 6.8.1.

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How to use this cheat table?

Install Cheat Engine
Double-click the .CT file in order to open it.
Click the PC icon in Cheat Engine in order to select the game process.
Keep the list.
Activate the trainer options by checking boxes or setting values from 0 to 1