So, I saw that randomizers had no guides, so I decided to make a guide for a couple of tips to help people out with their run. This guide also contains spoilers, continue at your own discretion. Once 1.3 comes out this guide will be updated accordingly.
How to get any item/infinite items
Know that should you be doing a Nuzlocke as well, this part of the guide might not be preferable due to the power it could give you at a relatively early point.
Once you get access to Roggan Town (post-gym 2), you will be able to rock smash 5 stones. These stones are located towards the middle of Roggan Town and are unavoidable. Rock smash drops are randomized meaning you can get anything besides key items and other specific items. These include things like pokeballs and mega stones. To deal with the pokemon from rock smashing get a pokemon with the ability run away, a pokemon with a smoke ball, or a pokemon with really high speed such as a ninjask. Smoke ball would be most preferred and you will likely get one from rock smashing.
JUST A NOTE: It should be known that on Randomizers there is no way to farm normally. What this means is that you will have the same chance of getting an oran berry as you do a heart scale when smashing rocks. This method is unreliable for this reason. Also, Crystal Pieces might not be able to be obtained in this way.
There are other methods of getting items besides rock smashing. Most shops in the game will have randomized items for sale. This includes places like the battle frontier, the better competitive item guy in murk forest, and every other shop that is not a pokecenter or Professor Pine in Holon. These two are the only exception to the shop randomization. One other exception is the Oval Stone not being randomized. It will still be available for sale in the black market. There is one simple reason why this method is not as good as rock smashing. The items that are up for sale are up forever. They will never change unless it’s a different save file. Rock smashing will give you many more unique items and useful items.
Also, should you get an item stealing move you can steal the item from the opposing Pokemon in the wild, as I believe every wild/trainer pokemon has a held item. You won’t be able to steal items from trainers and keep them however. Egg pokemon are an exception, as they don’t have held items.
Since every pokemon is randomized it can be frustrating to battle a weezing and it uses only destiny bond and you get knocked out. However, you can predict any pokemon’s moveset. Every pokemon will use its four most recently learned moves based on that pokemon’s ORAS moveset, for example, a level 43 Kadabra would have Future Sight, Role Play, Psychic, and Ally Switch.
In the case of major trainer battles past Xavier, they will have a mega evolution pokemon with a mega stone on their team. For example, in the Whirl islands Audrey fight, she normally uses a mega Crawdaunt, she might now use mega Pidgeot or mega Sudowoodo or even mega Rayquaza.
Eggs given out by Shady egg dealers are entirely random. You have the same chance of getting a weedle as you do an entei. You can also get evolved pokemon inside of eggs this way.
Finally, trades are random, but the basics of the trade are not. What this means is that to get the “delta Koffing” in the Miara trade center you still need to give a pseudo-legendary. To get “delta dwebble (cake)” you still need to trade a random pokemon for a random pokemon. Though, while I can’t be 100% certain of this it might be possible that trades that ask for certain pokemon types might ask for pokemon of a different type. I say I am not certain of this since I forgor.
What is and isn't randomized
So while there are a lot of things that get randomized in the randomizer challenge mode, there are some things that aren’t:
Pokemart items are not randomized, this includes the secret base one as well. Professor Pine in Holon is not random as well.
Key items are not randomized for obvious reasons.
Dev Island battles are not randomized as of 1.2.5, so if you have a version before that they will be randomized.
Darkrai Cult Mew is not randomized.
Pokemon types will not be randomized, there aren’t any water-type Porygons meaning Professor Sylvan lied.
All pokemon will have their ORAS learnsets meaning that no moves are randomized so there won’t be any Draco Meteor Poliwags.
All wild or trainer pokemon will have their four most recently learned moves via ORAS learnsets.
The number of pokemon a trainer has will remain the same, this goes for any battle including the rematch champion having 8 in hard mode.
Trainer’s names and appearance.
Meloetta puzzles and mysterious scrolls will remain unrandomized.
Clothes will not be randomized, it would be strange if they were.
All pokemon in friend safari’s will remain unrandomized, this means that despite not being able to trade, you can actually upload your base and visit others.
Level trainers and EV trainers are not randomized.
Crystal pieces are not randomized due to the power of having any of the Insurgence Primals right at the beginning or making the E4 even easier than it will already be.
Starter Eevee, for whatever reason, is not randomized.
So now here are the things that are randomized:
(Almost) every pokemon including static, gift, and starter pokemon.
(Almost all) Trainer battles.
Every item picked up will be randomized excluding key items (TMs picked up will be randomized but the number they are will not).
Held items will always be randomized.
Items sold outside of pokemarts will be randomized, this means that people in the black market could have mega stones. Only exception is that Professor Pine in Holon sells all the normal items.
Items on the ground will always be randomized (with exclusion of key items) this means you could find D. Volcarona armor disguised as a potion in the first ten minutes of the game.
Pokemon will not follow a specific pool, so you won’t find the same 6 pokemon in the Shade Forest meaning you can encounter any pokemon at any time.
Egg pokemon outside of maybe the daycare will always be random.
Trades are always random.
You can obtain items outside of the normal pool, this includes poffin berries and certain high money items.
Items and pokemon obtained through Sonata Tracks and Torren game corner.
Despite mega pokemon with mega stones being randomized to other pokemon with mega stones, legendaries won’t randomize to other legendaries meaning you could fight Zenith at the infernal base without him having any legendaries, the drawback to this is that any pokemon could be legendary including Megas.
Shiny Deino mission will randomize into any shiny pokemon I believe. Also, every radio tower mission is random.
The Primal Giratina and the Primal Regigigas fight will randomize into any of the 5 primal pokemon.
All hidden grottos pokemon and items except for sprites will be randomized.
This also ties In with infinite items as you could get these while also getting any item/infinite items. In a randomizer, money is actually more obtainable due to the larger item pool. Many items can net you large amounts of money. Some of these include:
Relic Copper - 1000
Relic Silver - 5000
Relic Gold - 10000 (or potentially 30000 due to Insurgence following the rules of ORAS)
Relic Vase - 50000
Relic Band - 100000
Relic Statue - 200000
Relic Crown - 300000
Nugget - 5000
Big Nugget - 10000
Big Pearl - 3750
Pearl String - 7500
Comet Shard - 15000
Balm Mushroom - 6250
Star Piece - 4900
Slowpoke Tail (?) - 4900
Big Mushroom - 2500
Stardust - 1000
Rare Bone - 5000
Something I noticed is that some pokemon have smaller pools that they then randomize from. These include the Mega pokemon and the primal fights. So to make the randomizer challenge run a little more difficult the devs decided to make it that all pokemon that could mega evolve would be randomized into a different mega pokemon with its mega stone. For example, at the Damian fight in the Dream Realm he normally uses his starter mega, let’s say he picked Eevee, now he could have a mega Gyarados or maybe a mega Slowbro.
As for the primal pokemon, in these three fights they randomize into either Kyogre, Groudon, Arceus, Giratina, or Regigas with respective crystal pieces or orbs (now this isn’t certain but I believe they can’t randomize into what they were before, you might not ever get a Primal Regigigas when encountering it at Holon Core).
I really hope that this helps you with your run, more information at The Wiki’s Page on Challenge Mode.
P.S I see a lot of people clicked the “Randomizer question” link below. It’s just a link back to a post that referenced this one.