At Level 100, 1 IV boosts a stat by 1 Point. At Level 50, this is 2 IVs for 1 Point.
This means a Pokemon's stat can go up from a value of 283 with 0 IVs to 314 with 31 IVs. If used in competitive, this can mean the difference between a Pokemon hanging on with 1-31 HP to a KO and is highly recommended to have 5 IV or 6 IV Pokemon.
Of course, when battling with your friends, you can do all of the crap you want ,1like Metronome battles. So IVs don't really matter here.