General Information

Version Differences
The Legacy Collection 2 Version is preferred for this game for a multitude of reasons 
 
 It loads significantly faster 
 It allows easy selection of region/language-version (see below 
 
 The US-English version should be avoided. Damage tables have the player deal less damage to mavericks. 
 
 Japanese is generally fastest 
 UK English has the better (for the player) damage table even with slower text, and should be played over US English if you want to read english text.

Upgrade Chips
Rescuing Mavericks in this game potentially gives the player upgrade chips. These can be given to characters to get better abilities 
 These should generally be given to each character's "Special" row, as the third unlock extends player invincibility frames three times the normal duration. 
 Power upgrades should be avoided, as they do not function as advertised (30% extra damage, take half damage, etc) 
 Other upgrade notes 
 
 Zero's fourth special upgrade, "Critical damage", applies to special attacks, like his Tornado 
 Axl's speed upgrades give his faster movement 
 X is generally not upgraded in New Game, as he is unlocked too late. 
 In a new game +, all upgrades can be unlocked before beginning.

Weapons
Ultimately X7 has 2 weapons with the most utility 
 
 Volt Tornado (from Tonion), including Zero's attack, are extremely busted and overpowered. Most fights, including the Tonion Refight, can be described as "Spam Tornado" 
 Axl's Explosion (from Gungaroo) is also Overpowered. It makes an extremely effective base damage attack, and is used against many bosses (including Final Sigma)