What are some lesser known tips and tricks that you know about?

Fun fact the girl that gives you berries in Sootopolis City (6:26) is meant to be Masuda's daughter who was born shortly before the release of Pokémon Ruby and Sapphire.

Corsola, chinchou, relicanth, and clamperl on Route 124 and 126 have a 5% chance of holding a shard (red, yellow, green, and blue respectively) which you can steal with Covet or Thief and trade them for evolution stones from the treasure hunter just outside of Mossdeep City.  It's at least some way to farm stones if you need them.

I have such a weak spot for gen 3 games. It was like they unlocked the holy grail of what they were missing, that music, the mechanics, the pixel graphics, the zone all just made three of the most iconic games I have ever played.

Tip; if you're looking for a dragon scale it's much easier to get them off of Bagon than horsea. It's the same chance for each, but encountering multiple Bagon is so much easier than horsea. Spent hours looking for one on horsea before I found out bagon have them too. It took 12 minutes after I went to meteor falls.

The fact that these games are so old and theres still so much stuff to talk about it 20 years later
Gen 3 best gen you earned a subscriber

I have some tips for speeding up the daily berry route.

As for how you want to plan your route, that's up to you and how many patches you want to visit, but the more you do, the more this method will save you time.

Typically you go to an area with berry trees growing in soft soil, and after collecting your berries in the area, you go to each individual tile and press A to open multiple text boxes.

'It's soft, loamy soil. Want to plant a BERRY?'
> Yes
(Menu pops up)
'[You] planted one [berry] in the soft, loamy soil.'
> Interacts again
'One [berry] was planted here.'
'Want to water the [berry] with the WAILMER PAIL?'
> Yes
'[You] watered the [berry].'
'The plant seems to be delighted.'

Per tile. This is PER TILE!

To save time, you can instead open the Start Menu, and go to the berries pouch. Because the menus have memory, the cursor and active bag slot are the same the next time you open the menu. Also the menus are pretty responsive!

In the berries pouch, you can select a berry and select 'USE'. Boom, done. As for the Wailmer Pail, you can register it to the Select Button. It saves so much time, and can easily be changed back to whatever you want later (eg, the Bicycle)

The most obscure thing I know about Hoenn is there are two unique seedots who are called 'Dots'. One is a trade in Rustboro, and the other is a contest opponent. I wonder if the translator forgot!

Probably well known, but in emerald, you can Speed up Egg hatches by having a pokemon with the abilities flame body or magma armor in your party. There are multiple other overworld interactions with pokemon abilities, I just can't remember most of them. Most of them are probably unique to Emerald though. Also, Mach Bike is the best bike.

there are 3 spots the newscaster trainer cycles everytime you beat them, its a double fight and gives a lot of exp and money, you can fight them infinitely if you know their spots, then after a ton of fights they might bug out and never teleport to another spot, when this happen, just change location/route and you can fight them again asap

This may be both a late and odd tip but still: Get the TM Sludge Bomb.
Why is this a tip?
It's a little weird to aquire:
Once you have beaten Norman, head to Dewford. Go into the Community Center and talk to the people. Once you have beaten Norman a NPC will give you Sludge Bomb.
And yes, that's unnecessarily hidden so most people don't know that they can aquire TM Sludge Bomb in this game at all.

A pokemon with suction cups or sticky hold abilities helps you land pokemon on a fishing rod by a great amount. Catch a gulpin, have it as the first slot pokemon (it can be fainted if you want another pokemon to battle without switching) and you hardly ever fail to land a pokemon. This was especially great for Feebas hunting but works for any pokemon.

Still to this day, I wish Omega Ruby and Alpha Sapphire had more Pokemon Emerald features.

I've been trying to do Solo Runs of Emerald with every single stage Pokemon (up to Wallace anyway) so let me share a trick I've learned in that journey:
1. Catching a teleport mon can be very useful for the middle of the game. Badges 3ish to 5ish involve a good deal of backtracking, and having a Teleport mon can help with this. You can teleport right back to Mauville after encountering the villainous team at Meteor Falls, or teleport to Fallarbor once you beat Maxie if you want Return ASAP,  or Teleport to Rustboro as soon as you beat Flannery, or right to Mauville after beating Norman. You set your teleport spot to whichever Pokemon Center you entered last, so if you want to heal, use the PC at the Day Care on Route 117 or the house in the North of Route 111, and plan your Pokemon Center visits carefully, cause its easy to mindlessly walk into them as soon as you see them!

You can breed Pokemon that know TM moves if you accidentally used it.

Specifically there’s two ways: breeding with a compatible partner that already knows the move or simply breeding a male that knows the move with a compatible female that doesn’t. You can chain breed to allow a Pokemon to learn the move, so long as it falls within the same egg group link and isn’t Legendary/genderless.

That AFK method also works for hatching eggs, though it only gets you to when the first one hatches. Having a Slugma (or other Flame Body or Magma Armor poke) anywhere in your party also speeds up eggs, but only from Emerald onward. Same exact thing works in Sinnoh too. Unova and Kalos not as much, but they have unobstructed circles you can go around endlessly by holding a single direction in the subway station and Lumiose.

Additional Compoundeyes tip: The Compoundeyes poke only has to be in slot 1. The effect still works if it's fainted, so you can have Thief on something else and not need to switch. Though beginning in gen 4 there's an additional tactic: faint the Compoundeyes poke and then have something with Frisk and Thief in slot 2. This way you get items more often, and then as soon as you enter a battle it tells you if there's an item to steal.

I mostly just used Thief as a means of training those early-game Abra. Its Special in Gen 3, so it will do some really decent damage with Abra's Special Attack that early in the game

Learned this while playing pokemon Emerald. Not really a hidden tip/trick but pokemon heal if you toss them in the PC boxes. You just have to kind of drag and drop them in and then take them back out. I found using this method of healing was really helpful between the time frame of beating your dad, 5th gym, and transitioning into the 6th gym. This is the time before you get fly and you have to battle trainers by the berry master's place and up towards the weather tower and then deal with team magma/aqua. The weather tower has a PC box so instead of traveling back to heal at any Pokemon center, you could just do this instead. May save you a few minutes here or there. I still use this method of heal  even in other pokemon games where Pokemon centers are scarce but PC boxes are plenty. Hopefully this advice helps somebody!

In ruby there’s no leveling up for nuggets and rare candies nuggets are 4% chance 1% for rare candies

In Emerald Pickup was changed so Rare Candies are only obtained at level 21. But Zigzagoon in Route 119 are found at the twenties. Catch Six of them there!