Megaman 4-6
Notable Differences: (1) Can be killed even after a boss is defeated (2) Mega Buster Charge Shot (3) Charge Shot stays charged even after being hit (4) Alternate Pathways (5) Secret Areas (6) mini-fridge Eddie (FlipTop) that dispenses a random item (7) Two Fortresses (8) Optional Items
Difficult Robot Masters: Use "Skull Barrier (from Skull Man) against Dive Man. "Flash Stopper" (from Bright Man) does actually freeze Pharaoh Man if he gets a bit tough
Useful Weapons: Drill Man "Drill Bomb" clears barriers and destroys small units.
Review: Toad Man's stage gives me the most dread. The boss is a wuss but his stage limits your maneuverability quite a bit. Mega Man 3 Rush Jet (from Drill Man) was too powerful, so they decided to allow you to only move it up and down as it moves a slightly slower pace than Mega Man 2. Rush Jet is useful near the end of Bright Man's stage. Rush Marine (From Toad Man) is rarely utilized. Instead, the wire (hidden in a death-like fall of Dive Man's stage) and the Balloon (hidden on the next screen over in Pharaoh Man's stage) allows you to gain items and explore areas with ease within any of the fortress levels.
Megaman 5
Notable Differences:
(1) Charge Shot removed when hurt (2) Beat Companion (3) Weapon used
without firing (4) Mystery Tank refills all items (5) Rush Coil
redesigned to "hop" instead "spring" (6) Submarine Removed (7)
Collection Items (8) Action Sequences (9) Location changes (10) Weapon
doesn't appear on Weapon Bar after defeating Robot Master
Difficult Robot Masters: While each boss has a particular weakness, the Mega Buster is almost universally recommended over the special weapons, as it charges faster than in Mega Man 4 and the projectile is twice as large. "Power Stone" (from Stone Man) is effective against Charge Man but takes time to fire per shot. "Water Wave" (from Water Man) is effective against Star Man but you have to hit him on the ground. Amusingly, "Gravity Hold" (from Gravity Man) makes the battle with Gyro Man trivial
Useful Weapons: None
Review: The bosses are incredibly difficult if you don't know their attack sequence. The first fortress boss is perhaps the hardest of them all until you find out that Water Wave (from Water Man) destroys his bullets. Certain stages, like Crystal Man's stage, takes a lot of watching and waiting before taking action. Other stages, like Wave Man's, contain new minigames that completely removes the standard Mega Man environment. Many of the new items are useless. Unlike the wire and balloon in Megaman 4, Super Arrow (obtained by Star Man) is only useful in very few locations. Rush Marine was removed and Rush Jet still remains situational. Getting all 8 letters proved far too difficult for Beat. Though, I hear he is an attack maniac in this game.
Megaman 6
Notable Differences:
(1) Rush Adapters that transform Megaman (2) Larger and More Alternate
Pathways (3) Energy Balancer that allows collecting capsules to
automatically distribute to your weapons (4) Introduction to Robot
Master shows statistics (5) Megaman speaks (6) Color Palette changes
after Robot Master is defeated (7) Demonstration of what weapon does
after defeating Robot Master
Difficult Robot Masters: "Plant Barrier" (From Plant Man) on Tomahawk Man.
Useful Weapons: : Flame Man "Flame Blast" for clearing icicles and hitting the top of a target; Knight Man "Knight Crush" works well for brunt damage.
Review: Instead of collecting letters for Beat, you must utilize the new Rush adaptors. This means you must get Rush Power Adaptor (from Flame Man) and Rush Jet Adaptor (from Plant Man). The four plates are found in the following stages: Tomahawk Man, Yamato Man, Knight Man, and Centaur Man. Falling through the spikes inside Wily Castle is horrible. Tank-CS2 is also a horrible fortress boss. Use Wind Storm (from Wind Man) on him. I still wasn't able to tell how fast the fans were spinning in the game. Because of the new enhancements, there are tons of alternate paths available.