Dragoon- Owl's weapon
Owl- Cyberpeacock's weapon
Cyberpeacock- Mushroom's weapon
Spider- Beast's weapon
Beast- Ray's weapon
Ray- Walrus's weapon
Walrus- Dragoon's weapon
Mushroom's- Spider's weapon

Megaman X's Ultimate armor:-  Highlight Megaman X at the player selection screen. Press Circle(2), Left(6), then hold L1 + R2 and press Start. Note: Hold L1 + R2 until game play begins. For the Japanese version, press X(2), Left(6), then hold L1 + R2 and press Start. Enter a special armor capsule to receive the new armor. 

Zero's black armor:-  Highlight Zero at the player selection screen. Hold R1 and press Right(6). Release all buttons, then hold Circle and press Start. For the Japanese version, hold R1 and press Right(6). Release all buttons, then hold X and press Start. 

Animation sequences:-  Begin game play and leave the game unattended for approximately ten minutes. Megaman and Zero's animation sequences will eventually being to play.

Megaman's Ultimate Armor and Nova Strike:-  Enable the "Megaman X's Ultimate armor" code. Play through the first two introduction stage, then start the Jungle stage. Go halfway down the second waterfall and go to the right. Enter the capsule and to get the Ultimate Armor along with Nova Strike and the aerial attack.

Unlimited lives for Megaman X:-  Begin game play on the Frost Walrus stage in Area 1. Go to the section where the ice passages disappear. Turn to the left and get the extra life. Repeat the process to collect as many lives as needed.

Unlimited lives for Zero:-  Begin game play on the Cyberspace stage. Complete the first stage with a "S" rank. Collect the extra life, and repeat as needed. 

Hint: Capsule locations:

Armor capsule  -  Go to Magma Dragoon level and proceed until reaching the part of Volcano Area 2 where you have the armor. Get into it and dash jump towards the platform. Get on to the platform, then charge twin slasher to full power and destroy the blocks in front of you. Pass through and get the armor upgrade. 

Helmet capsule  -  Go to the Cyber Peacock level and get a S rank on the third stretch with the yellow balls that drains your energy. This is difficult to accomplish, but possible. 

Leg capsule  -  Go to the Web Spider level and proceed to the part with the waterfalls. When you drop down to the section below 
the part with the spike spinning on the platform, just go through the gap on the right side wall opposite to the hole. 

Arm capsule  -  Go to Storm Owl Area 2 with all the laser cannons. Get to the section with the hole in the ceiling, with spikes on the floor and each side of the wall. Use the lightning web weapon to jump onto the platform. Above it are two capsules. One allows your fire four shots in a row and the other allows you to fire a plasma bolt. The best choice is the plasma bolt, as it keeps hitting the 
enemy after the first hit. 

Ultimate capsule  -  Begin game play as Dark X. Go to the Web Spider level and proceed to where the leg capsule was located. 
Instead, you will receive the ultimate armor. This allows unlimited nova strike, unlimited none charged special weapons, hover in midair, and the ability to shoot plasma bolts. 

Hints:

E Tank:-  To get one of the E Tanks, go to the Cyber level and get the S rank. To do this, jump on the platform that does not have an enemy.

Defeating the Bosses:-  Each Boss have a weakness related to their own weapons. 

Dragoon: Owl's weapon
Owl: Cyberpeacock's weapon
Cyberpeacock: Mushroom's weapon
Spider: Beast's weapon
Ray: Walrus' weapon
Walrus: Dragoon's weapon
Mushroom: Spider's weapon
Sigma In Ghost Robe: Dragoon's weapon
Sigma Out Of Robe: Spider's weapon

Defeating the Spider Boss:-  When you get to the Spider Boss, dash slide away to dodge his webs, then jump over it.

Defeating Cyber Peacock:-  To defeat him with Zero, use the Z-Saber Enhancement you get from defeating Magma Dragoon.

Defeating Magma Dragoon and Slash Beast:-  As Zero, use Raijingeki, which does 2 hits on Dragoon and 1 hit on Slash Beast.

Defeating Web Spider:-  As Zero, use Ryuenjin after if you have Kuuenbu jump and slash him for an extra hit.

Easy helmet upgrade:-  Go to the Cyber Peacock stage. Get a rank "S" on the third section. This can be done easily by using the Soul Body (Split Mushroom's weapon) periodically. You can kill the floating eye balls.

Easy lives and energy:-  Go to Frost Walrus/Kibatodos stage. Then, dash jump towards the first wall on your left, then dash jump to 
the right one. Continue to the right. You will see two snowmen. Use either the Lightning Web (X) or the Double Jump (Zero) to jump higher and reach the upper-right edge. Defeat the weak enemies here and get a lot of energy capsules. If you have not taken damage, you should have one E-tank full at 50%. You should also get the life near the appearing and disappearing platforms. 
Return four times maximum to fill up your two E-tanks and get a good supply of lives. Note : For really tough fights (for example, Colonel and Sigma) and you have already used all your energy tanks, it might not be a good idea to pick up many lives. However, do it against the eight Mavericks once you meet them again, if you do not use tanks during the fight.

Float in mid-air:-  Get the fire weapon from Dragoon. Jump and repeatedly press Square to float in mid-air. It helps you do not 
have the Rocket Boots.

Double cyclone is effective in the air since it stops X short and gives him a little more time and distance. Charge up rising fire and jump in the air. When you reach your highest point in your jump, release the charge. You will boost up for a double jump.

Chill Penguin appearance:-  Chill Penguin from the original Megaman X game on the SNES can be found in the back ground of the Snow Base level at the Mid Boss frozen in ice.

Spark Mandrill appearance:-  Start Frost Walrus's stage and look closely in the background. A big frozen Ice block frozen like Spark Mandrill. 

Buffalo appearance:-  Get to the halfway Boss in the Frost Walruses stage to see the Buffalo from Megaman X3 in the background.