I need to point out first, that Tapus + UBs cannot be bred
You have to soft reset for natures. Pokémon with the ability Synchronise do this, like Gardevoir and Abra. There is a 50% chance of them passing their nature onto the Pokémon you're battling.
"From Pokémon Emerald onward, if a Pokémon with Synchronize is in the first place in the party (even if fainted), any wild Pokémon encountered has a 50% chance of having the same Nature as the Pokémon with this Ability." - Bulbapedia
And also for good IVs (I will put a link at the bottom of this post in case you need more information on them) You just have to SR (soft-reset) until you have IVs in at least the relevant stats.
Bare in mind in SuMo you can use Bottlecaps to max out IVs, so if you have bottlecaps you don't need to necessarily search for good IVs.
For example, if you want a Special Attacking Tapu Koko, the very least in terms of IVs you need is 31/x/x/31/x/31. That's 31 HP (Or a "flawless" IV) 31 Special Attack (because you'll be using Thunderbolt, D Gleam etc) and 31 Speed (To be as fast as possible). The x's are less important IVs, but the higher, the better. You will preferably want a Timid (or Modest, up to you) Synchroniser to get the correct nature.
In an ideal world, or if you are a perfectionist when it comes to IVs, for Tapu Koko the best you could hope for is 31/x/31/31/31/31, where x is Attack, which can be anything since you're a Special Attacker.
If you want a Hidden Power, it takes longer to search for because you're looking for specific sets of IVs, rather than just straight 31s across the board. For example, Hidden Power Ice can come in a variety of IV spreads:
30/31/30/31/31/31
31/30/30/31/31/31
30/30/30/31/31/31
31/31/31/31/31/30
31/0/30/31/31/31
There are many other combinations, and once you find the IVs for your caught legendary/UB you can use a Hidden Power calculator, just input the IVs and it will tell you the Hidden Power of your Pokémon:
http://www.psypokes.com/dex/hp.php
And here is an IV calc:
http://www.psypokes.com/dex/iv.php
So to recap:
1. Use a Sychroniser.
2. Catch the UB/Guardian, Check IVs in PC or on an IV calculator(+ Hidden Power if you need it), if it's not what you want, Soft Reset and do the same.
3. Repeat Step 2 until you have your desired Pokémon.
Hope this helps! If you have any questions PM me or post on the PF Discord #team_building :]
