Concept: One easy Gift Pokemon removes all the IV Grind once a Day Care is reached!

[SuperSpyroDragon64]

Right after the player selects their starter, gift the player character a low-level Ditto with perfect 31 IVs across the board holding a Destiny Knot. And let the player access a Day Care in the starting town that also sells Nature Mints.

And just like that, resetting over and over for good IVs and the desired nature is a thing of the past! When a Pokemon breeds while holding a Destiny Knot, the resulting Egg inherits all of that Pokemon's IVs.

Give the player a Ditto with perfect 31 IVs in every stat, and now any Pokemon the player desires can be bred with the Ditto for an Egg to hatch. And that Pokemon Egg will hatch with perfect IVs!

Ditto is also an excellent early-game Pokemon that promotes strategizing on the fly, as the Impostor Ditto copies many pokemon and makes the player familiar with these Pokemon and movesets.

As an aside, ensuring the player starts with 2 Pokemon (starter, and free Ditto) means every player can enjoy Double Battles against Trainers+Gym Leaders and Singles battles against wild Pokemon.

 

[Corveone]

So you would get your starter, and a perfect Ditto, so you can immediately breed and replace your starter with a 31 IV copy of it. An unnecessary waste of time, just give everything max IVs (gift, wild and trainers' Pokémon alike) or simply get rid of IVs (like Legends Arceus), and breeding the Pokémon you just caught/received to get a perfect version of it won't be necessary.

 

[SuperSpyroDragon64]

Yeah turns out this is the better way. It even guarantees enemy Pokemon will have perfect IVs! And it lets you give any IV spread for Hidden Power usage without compromising the IV stat calculations.

 # Returns this Pokémon's effective IVs, taking into account Hyper Training.
  # Only used for calculating stats.
  # @return [Hash<Integer>] hash containing this Pokémon's effective IVs
  def calcIV
    this_ivs = self.iv
    ret = {}
    GameData::Stat.each_main do |s|
      ret[s.id] = 31#or whatever the maximum IVs are in your game, I personally set it to 32
#      ret[s.id] = (@ivMaxed[s.id]) ? IV_STAT_LIMIT : this_ivs[s.id]
    end
#end
    return ret
  end