Megaman X4-5
Below you will find my opinions on Mega Man X4 and X5
Megaman X4
Notable Differences: (1) Choose to play X or Zero from start of the game (2) Option to change buttons (3) Energy capsules land closed and then open (4) Weapons recharge when you die (5) 1-Ups glow (6) Maverick Attack Patterns based on Street Fighter Moves (7) Able to use Ride Armor against a Maverick (8) Japanese Weapon Names left in (9) Armor Cheat Codes Before Starting Game
Difficult Mavericks (using Zero): Use Ride Armor first time around and "Raijingeki" aka "Thundergod Attack" aka "lightning" (From Web Spider) against Magma Dragoon. Use "Ryuenjin" aka "Dragon Flame Blade" aka "fire" (From Magma Dragoon) against Cyber Peacock. Use "Rakuhouha" aka "Aiming Laser" aka "peacock" against Storm Owl if he proves difficult.
Useful Weapons (using Zero): "Kuuenbu" (From Split Mushroom) allows you to double-jump (which then doesn't allow you to dash) and the ability to fall to the ground with a somersaulting saber. The other abilities either have slight passive improvements or attack patterns with both positive and negative changes.
Review: The graphics of the game is stunning. Just take a look while going through the jungle or while running up the stairs. Even the "Ready" screen has a cool 3D effect. It was super fun playing as Zero. The only problem using Zero is not being able to exploit a Maverick's weakness. Most of his upgrades give him an additional way to strike foes instead of gaining abilities. Though, you still get fire, ice, lightning, and "peacock" elements. I enjoyed the anime cut-scenes but the story is pretty depressing. Unfortunately, I was unable to defeat the Mavericks during the Fortress Rematches. It would be rather interesting to replay the game as X and be able to use charged abilities alongside armor upgrades.
Megaman X5
Notable Differences: (1) X and Zero can duck (2) You can choose to play as X or Zero before but not during a stage (3) Armor Sets instead of Armor Pieces (4) X's Shots can't go through walls (5) Ropes (6) Continue Places you Upon Death Checkpoint instead of Beginning or Midway Point (7) Able to enter Fortress from the Start (8) Saved Games consider what station of the Fortress you are in (9) Virus System (10) Rescue Reploids (11) Game Times and Scores (12) Hour System (13) Hint System (14) Training Level (15) Weapon Screen offers Short Description when highlighted (16) Three Difficulty Modes (17) Mavericks have Guns N' Roses names in the manual (18) Three different endings (19) Both characters gain weapon ability regardless who finishes the stage
Difficult Mavericks: None. (Zero's Blade is able to deal more than enough damage)
Useful Weapons: "Dark Hold" (From Dark Necrobat) freezes time (both for X and Zero). "Crescent Sword" (From Crescent Grizzly) allows Zero to double-jump and his saber swipes in a complete circle when he uses it in the air. The counterpart "Crescent Shot" charged ability (gained at the same time) gives you a brief energy shield. The Zero ability "Twin Beam" (From Spike Rosered) gives you an untouchable duplicate in front of yourself that is still capable of dealing damage.
Useful Armor: Starting the game with X (and not Zero) gives you "Force (Fourth) Armor" with increased defense, Plasma Shot, Hover Boots, and the ability to charge special weapons. "Falcon Armor" gives you the ability to fly, making you invincible to enemies and even certain bosses (it does take away your charge special weapons and air-dash capability).
Review: I'm going to come out and say that this is the first time it didn't feel like a Mega Man game. I also have to add that they radically added unpolished features without any explanation, whatsoever, to how they work. Because you are able to use infinite continues, the EX Tank and even essentially lives in general become redundant. The new virus system poisons X after 5 infections but actually makes Zero invincible after 3. I found it incredibly unlikely to even worry about viruses seeing the number of ways they can wear off. Rescuing Reploids give you life energy and a 1-Up. They become "un-rescued" if you die during the stage. Alia keeps giving you hints throughout the stage, whether you like it or not. You can't turn her off. The music, especially during the Fortress bosses, is terrible! It was so bad, I had to turn off my speakers.
Eurasia Notation: I have to include this in another subcategory. The game challenges you to destroy the space colony "Eurasia" within 16 hours. Each time you join a stage or fight the harassing "Dynamo," you lose an hour. Your attempt to shoot it down with the giant cannon "Enigma." If that fails, you try again with a space shuttle. To improve your chances, you can gain 4 parts in the Maverick stages. However (especially in the X Collection), your chances won't reach 100% in Normal or Hard. In fact in my play-through, I went crazy to find out I failed to destroy it even with all parts collected with a 50% and 64% rate respectively. This made me unable to use Zero for the rest of the game and would have gave me the bad ending.