There are a number of collectible items in MegaMan X: Corrupted, including consumables, permanent upgrades, situational items, and other secrets. These can be found by X, Zero, Axl, or Synthia.

Consumables

These items can drop randomly from defeated enemies or found in stages at fixed locations.

Life Energy
Restores lost HP, or fill the Sub-Tank when HP is full. Restores 3/6/16 HP for a small/large/huge capsule.
Weapon Energy
Restores energy used by special weapons. Restores 3/6/16 WE for a small/large/huge capsule.
Combo Energyy
Restores both HP and weapon energy, and only drops while the Hydra helmet is equipped.
Extra Life
Gives the player 1 more attempt to continue from the last checkpoint after dying.

Anti-Consumables

If Plasma Puffer's Final Four is in effect, pre-placed items in stages will have the opposite effect.

Upgrades

These items grant permanent upgrades upon pickup and are difficult to acquire. When playing as X or Zero, these upgrades affect both characters.

Skill Capsule:Unlocks the Skill Tree, and is later used for Air Mobility enhancements.
Heart Tank: Permanently increases HP by two points.
Sub-Tank Expansion: Permanently increases the capacity of the Sub-Tank by 4 points.
Rare Metal: Adds a large amount of experience.
Supply Crates: Collect them to upgrade the base.