Accidental Pervert: When Vargas first encounters Li Fang, she accuses him of trying to look up her skirt. Given that Vargas is the resident Lovable Sex Maniac, one would generally assume it was intentional on his part, but given that Li Fang dresses in a Showgirl Skirt and was walking up a set of stairs in front of him, it's more ambiguous.
After the End: The Great Fall, which killed 90% of humanity in a week, took place sixty years before the game begins. Thanks to the G Systems (which are basically Matter Replicators), the world recovered in fairly short order, if quite a bit emptier than before.
Anti-Grinding: You don't get massive amounts of experience from random battles, and leveling only increases about a third of your offense-oriented stats (and none of your defense ones).
Money Grinding: You probably will have to grind out money for equipment and weapons though.
Armor-Piercing Attack: A certain melee skill line and critical hits both go through defence, making them invaluable against heavily armored enemies that can take no damage otherwise.
Arms Dealer: Vargas is a Sky Pirate who also owns and controls the international Black Market, but he's actually a pretty nice guy. Mr. K is a legitimate weapons supplier for Eisengrad, but actually sell weapons to their enemy Dark Alliance as well.
Attack Drone: UC Gundams bits and funnels make an appearance as techs that can be powered up by the right equipment.
Awesome, but Impractical: Shield cannons; as shields with built-in weaponry, they theoretically provide the benefits of both a shield and an arm-mounted weapon. Unfortunately, they tend to be large, relatively weak as both weapons and shields, and have significant speed penalties.
Some Boost Attacks have no real use. Explosion uses one of your ranged weapons to deal damage to all enemies in a huge Wave Motion Gun style attack, but since it just divides the normal weapon damage up between multiple targets, it ends up being fairly weak. The Speed Lance line of attacks allow you to make a melee attack before anyone else can act, regardless of Action Initiative, but in late-game this does more harm than good since it doesn't allow your allies to set up support moves to cover you from Counter Attacks.
Awesome yet Practical: Some of the most useful Boost attacks are Gatling Fire and Lightning Lancer. Gatling Fire fires all ranged weapons in one turn and is available to nearly every character, while Lightning Lancer is a melee attack that automatically goes first regardlesss of Action Initiative and (unlike normal melee attacks) is not vulnerable to Counter Attack.
BFG: Its Gundam, several of the big weapons make appearances. Large handheld weapons actually can't be used to snipe though.
BFS: The aptly named Large Beam Sword, the ZZ's Hyper Beam Saber and the Sazabi's Beam Tomahawk Sword are equippable.
Big Damn Hero: Hal in the Gelgoog than the Gundam, Fritz and his Full Armor Gundam, plus and again Hal during the final dungeon.
Bigger Stick: New weapons and Mobile Suits are necessary at regular intervals if you want to survive.
Bishonen Line: Done with the Big Bad's mecha. He starts off in the Master Gundam from G Gundam than upgrades to the nonhumanoid Alpha Azieru mobile armor, and when that's defeated he uses the G-System to reconfigure it into an evil version of Wing Zero Custom, which has a more familiar humanoid appearance.
Blocking Stops All Damage: The Double Shield boost well stops all damage, even moves that cannot otherwise be blocked by other boosts.
Bonus Boss: Numerous examples, spread throughout the game. Sometimes they're simply waiting at specific places on the Overworld, other times they're found in a Bonus Dungeon.
Bonus Dungeon: A few dungeons don't have to be completed but can to aquire powerful equipment. Usually have a Bonus Boss guarding the really good stuff.
Boobs of Steel: The melee-oriented ladies (Tremmie, Rezner and Li Fang) are more stacked than the ranged-focused girls (Aeon and Lapis).
Boring, but Practical: The defensive and shutdown boosts don't do any damage but are essential to beating most bosses after a certain point.
Boss in Mook Clothing: Every other area has atleast one enemy that would be a Mid-Boss battle as a random encounter.
Can't Catch Up: Starting with the second mobile suit you get, it becomes clear that some mecha just flat-out overpower others. Given that you can only build a limited number of MS during the course of the game, and many of the ones you built are unique, you'll frequently have to settle for a subpar ride for some of your characters.
Charged Attack: Boost attacks, which require you to use between 4 and 10 units of energy, generated at 2 units per turn (unless you use items, equipment or abilities to increase it).
Char Clone: It wouldn't be Gundam without one! Hal has all the classic attributes of a Char.
Commissar Cap: Rezner wears one, as do a few other Eisengrad officers. You can give her a beam pistol for extra Commissar points!
Counter Attack: Both enemies and allies automatically counter a melee attack on them with a melee attack of their own. Learning to deal with these is absolutely vital for the proper use of melee-oriented characters.
Crapsaccharine World: Don't let the cutesy look fool you, its still Gundam. The backstory alone kills 90% of the population.
Critical Hit: Works differently here, they do somewhat more damage and ignore defence. Little help for the attacks that already ignore armor.
Crutch Character: Gavenger, who has good ranged and melee stats, all three basic defensive boosts, and a great healing ability. No other character has this combination of abilities. And he is the only character who the heroes lose.
Darkest Hour: The aftermath of the Dark Alliance base fight. Hal is revealed to be Vladi, and he has allies with suits vastly more powerful than the Dark Alliances. Gavenger and Major Rezner both sacrifice themselves to give the others a chance and all they can do is run.
Eleventh Hour Superpower: The Nu Gundam — which has the largest possible equipment grid and among the best stats in the game — is only available after the penultimate boss fight. The Sazabi, similarly powerful, only joins in for the second half of the Final Boss. You'll need them both for the Post-End Game Content.
Glass Cannon: Both Tremmie and Li Fang deal damage fast and hard, but lack defensive boosts. A number of MS with good melee or ranged stats but poor HP and armor stats also qualify.
Godzilla Threshold: The villains go to the moon in the last part, so Tristan and friends need to make a spaeship to pursue. The leader of the Unicorns at first objects because a spaceship could potentially make another Great Fall, but because of the threat presented relents.
Grand Theft Prototype: Wouldn't be Gundam without one! But Aeon of all people did this in the final stage to Neo Zarth's newly built Wing Zero Custom out of convenience. Turns out they can make a stronger copy.
Grid Inventory: Used to equip weapons. Each mobile suit's inventory is a rectangle of a certain height and width (the smallest is 3x4, the largest is 8x8), and each weapon is represented by a certain arrangement of squares. Melee weapons tend to be tall and skinny, while ranged weapons are short and wide; for example, a basic beam saber is one square wide and three tall, while a basic beam rifle is only one square tall but three squares wide. The dimensions of the grids reflect this as well; a melee-oriented suit will be have a tall, thin grid, while a ranged-oriented suit will have a short, wide grid, and a balanced suit will have a nearly square grid.
Infinity–1 Sword: You have to make do with a few suits that don't quite measure up to the fully top tier ones. The Bonus Dungeon Mount Trial has three that can be used for the pilots that don't get them.
Infinity+1 Sword: The Nu Gundam is pretty much this. It has the highest speed and ranged stats and has some of the higher strength and armor as well as having a full 8x8 inventory grid. Burning Gundam can be considered one as well solely for its melee stat, which is way off the roof.
Jack of All Stats: Quite a lot of suits, notably the GM series of mecha. Generally averted for the characters; all of them focus on something.
Jail Bait Wait: Referenced by Vargas when you talk to him at Rock Diggins regarding Lyra.
Lazy Backup: Used simultaneously in two different ways; your team consists of six characters, split into three "active" characters and three "reserve" characters. You only get six even if there are more characters available at that point in the plot, and if your active three are defeated, it's Game Over even if your reserve three are in perfect health.
Lethal Joke Character: Li Fang first appears in a Guncannon (a ranged-oriented suit) using barefisted melee attacks. She's still rather impressive in it.
Let's Play: has an impressive one Here at the lparchive. Has humor, Fritz bashing, but is played by a person who self-admittedly makes tactical errors and refuses to finish the Bonus Dungeon.
Magic by Any Other Name: MS Saga calls them "techniques" instead of "spells", but they're still magic, complete with a pool of "Technique Points" instead of MP and a stat ("Mind") that controls how powerful a character's techniques are.
Metal Slime: Metal Zaku and Gold GMs both have low HP and give, respectively, large amounts of Experience Points and money with a chance to drop rare e-caps. To offset this, they have tons of speed and defence — to the point they always go first and cannot be damaged by anything other than a critical hit or armor piercing attack. With their ability to run away from a fight and disable your MS, you're never guaranteed a win. The most powerful of these are a full up Bonus Boss.
Mighty Glacier: Tristan, Gavenger and Bazuli all have considerable offensive abilities but are also slow. Several MS with good HP and armor but low speed also qualify.
My Rules Are Not Your Rules: Enemy suits have loadouts, abilities and powers that you cannot duplicate, without even counting the MS that you don't have access to.
Neutral No Longer: Vargas was willing to wait out the war as an arms dealer. When the Dark Alliance uses his G-System to make mobile suits for there own designs, he decides to take the fight to them. He doesn't hesitate to help in the next war when he hears that Tristan and friends are in danger.
Nintendo Hard: The final stages of the game and the bonus bosses. The latter can easily kill you in one hit.
Now, Where Was I Going Again?: Pretty bad at this. You can ask your teammates to get a vague idea of where to make the next storyline stop and don't expect much help keeping tabs on the sidequests.
Opposites Attract: Vargas shows the most interest in Li Fang who, in both gameplay and personality, is his complete opposite.
Overly-Long Name: Marie Orijin Neikeshuneku Tokita. We only get to see the full version once.
Padded Sumo Gameplay: Once you have a high enough level to stop virtually any attack, the bosses get enough HP, armor and immunities to make fights last quite a while. It takes hours to beat the Bonus Boss with a fully prepared party.
Palette Swap: There are relatively few actual enemy models in the game. Some of the more obvious ones include bosses like Big Zam or the Gundam Wing Gundams that show up again later, with different colors and more power.
Post-End Game Content: An odd example; after you beat the Final Boss, you can save. When you load that save, it drops you at the save point immediately before the final boss, as if you hadn't beaten him yet — except that the Eleventh Hour Superpower that you acquire during the final boss battle is still there, and now the Bonus Dungeon is open
Power Up Letdown: You can often invest a lot of time, money and resources to acquire equipment and mechs that aren't much stronger or even weaker than what you already have.
Senseless Sacrifice: Gavenger, staying behind to execute a You Shall Not Pass after the party has been chased into a small tunnel. He dies, which is considered stupid by some players since he could have just collapsed the mouth of the tunnel, and some of the enemies' suits are too big to follow the party in the first place.
Sorting Algorithm of Evil: Justified, in the beginning the resident authorities on technology refuse to research weapons tech, which leads to both sides using only the most basic of equipment. Later on, villains have access to the more advanced tech.
Standard Status Effects: Same old effects, shiny new names to make more sense as applied to giant robots. Acid is poison, Short is paralyze, etc.
Super-Deformed: The mecha of all things, are semi-SD. They're about halfway between their normal "realistic" proportions and their chibified SD proportions. This means that they're about 30 feet tall (instead of the usual 60-or-so) and more stylized than the typical depiction of mecha, but not to the point of being cutesy looking or their heads making up 80% of their bodies. The humans, though, are still normal.
Suspiciously Similar Substitute: Downplayed; more than once, after a character leaves the party, a similar-seeming character will soon show up. But each time, the new characters won't quite be able to replace the old one seamlessly, due to differences in their stats and boost attacks. The effect is more like Ryu and Ken than a straight-up clone.
Too Awesome to Use: Engine energy equipment and high-stat boosts can turn the tide in many battles. Too bad you can't buy them.
Wake-Up Call Boss: The first Gouf will teach you the importance of defending against boost attacks. The Xamel shows the necessity of defensive boosts.
With This Herring: Averted; top-tier (for the time) mobile suits are given to you at multiple points in the game. Don't expect much help upgrading them, though.