Traditional Mega Man games are very much alike, but they are also very different. There have been curious differences in gameplay, some which change strategies, and some which make the game more or less annoying to the player. Here is a lowdown of the different stats and what they mean:
Open Menu: This stat determines whether the player can open the Weapons Subscreen while a boss is introduced and their energy meter is filling up. If "Yes", the player can can see who they are up against and switch to the proper Special Weapon while the boss strikes their pose. If "No", then the player will have to have switched Special Weapons before entering the battle, or give up their initiative. This can be especially annoying for the player in areas with teleporting hatches.
Charge Up: This stat determines whether the player can charge their weapon during a boss's introduction. If "Yes", the player can start the battle with a fully-charged shot from a Buster or other Special Weapon all prepared and ready. If "No", the player will want to charge up before entering the battle -- with some teleporting hatches however, this cannot be done.
Lose Charge: This stat determines whether the player loses the charge on their arm cannon or other Special Weapon if they receive a blow from an enemy while charging up. This can be especially annoying for the player when they are in the heat of battle and desperately trying to charge up, and yet keep getting hit in the process.
Horizontal Recoil: This stat lists how many game tiles (square blocks) the character typically bounces back whenever he is hit. If this number is over 1, the player will have to be extra careful to avoid being knocked off the ledge they are on and into spikes or a pit.
Vertical Recoil: This stat lists how far the character will fall after getting knocked off a multi-screen ladder before the player is allowed to grab onto the ladder again and halt their descent. This usually increases in proportion to the horizontal rating (later games have been eliminating long vertical sections with ladders so this rating not usually present).
Shots On Screen: This stat determines whether the player can open the subscreen while one of shots fired from their weapon is still on the screen. If "No", the player will have to be aware when using the menu in order to pause the game.
Fall Off Ladder: This stat determines if the player was on a ladder when they opened the weapons subscreen, which upon closing, the character would instantly start to fall. This has been taken out of later games, mostly ones in which the screen changes to the menu as opposed to it popping up onto the game screen.
Paused Refills: This stat determines if the game pauses while the meter refills one unit at a time whenever the player picks up an energy pellet or capsule (provided the meter was not already full). This can throw off players who are new to the series, and has been removed from some of the later games.