Wide Lens — Boosts holder's accuracy by 10%.
For example, if you had the move DynamicPunch, which has 50% accuracy, the Wide Lens would increase that to 55%. If you had the move Hydro Pump, it would increase the move's accuracy by 10% of the base, so the 80% accuracy would become 88%. From Generation 5 onwards, it uses a multiplier of 4505/4096.
Zoom Lens — Boosts holder's accuracy by 20% if the target has already used a move the same turn.
This works well on slow but powerful Pokemon, such as Conkeldurr and Slaking. From Generation 5 onwards, it uses a multiplier of 4915/4096.
Micle Berry — Boosts the accuracy of the holder's next move by 20%.
The Micle Berry activates when its holder is at less than or equal to 25% of its maximum HP (or 50% if the holder has the Ability Gluttony). From Generation 5 onwards, it uses a multiplier of 4915/4096.
X Accuracy — When used from the bag in battle, raises a Pokemon's accuracy by 2 stages (Generation 7+), 1 stage (Generations 3 - 6), or makes the Pokemon's moves guaranteed to hit (Generations 1 - 2).
Its effects wear off after the battle or when the Pokemon you used it on is switched out. In Generation 5 link battles, there is a special feature known as the Wonder Launcher that allows you to use exclusive items. These are the X Accuracy 2, 3, and 6. These items all boost your accuracy by 2, 3, and 6 levels respectively.
The Wide Lens, Zoom Lens, and Micle Berry are available in every game starting with Generation 4, and the X Accuracy has been obtainable since Generation I. Please reference Bulbapedia for game-specific locations: Wide Lens, Zoom Lens, Micle Berry, X Accuracy
