Xenogears

Deathblows

Fight your non-boss, non-Gear battles the following way unless you run into trouble: cycle through EVERY possible Square, Triangle, and X combination that does not end with a X. This is because ending something in a X will start a Deathblow. So if you have 4 AP, you should do:

Round 1: T-T-T-T

Round 2: T-T-S

Round 3: T-S-T

Round 4: S-T-T

Round 5: S-S

Round 6: X-T

Round 7: Repeat

Adjust the pattern as you get more AP, and of course if the battle ends before you reach the end just try to remember where you left off last battle. This is important because you will optimize your Deathblow learning efficiency, and will in fact master Deathblows before they are even available to you. Since Deathblows are largely more important than leveling up, this will save you a lot of time grinding or otherwise wasting your time trying to learn Deathblows.

You don't really need to know anything else besides the Deathblows leveling trick, everything below is just a nice bonus.

Bosses that self-destruct almost always give better items if you kill them before they do so.

Buy three Tank Guards. At a certain point they disappear from all available shops in the game and you can't buy them again, so get them as soon as you see them. Don't worry about most enemies, but you'll know when you need them.

Stuff equipped on your human character ALSO affects them while in their Gears. There are many, many items that bestow insane abilities on Gears when their human pilots equip them.

When you first gain control of Fei at the beginning of the game, check under Fei's bed for free money.

When you fight the kid from your village at the Fighter's Tournament (or whatever it's called), don't attack.

Your chance of Hyper Mode is mostly determined by your amount of lost health you lost this battle and number of attacks you make. Basically, almost dying will give you a large enough percentage (40+) to almost make it useful but then you will die soon.

If you want to play the game normally and fight battles with their intended difficulty, DO NOT USE DEFENSE INCREASING ACCESSORIES.

Character equipment such as evasion and speed shoes, can affect you Gear as well. Ether defense also determines a Gear's stat.

Ether attacks become broken when you find the equipment that increases their attacks and use elemental buffs and debuffs with your Ether abilities.

Using fire Ether on some enemies will make them drop better items you can sell for good bits of cash. It is a really nice addition to cook your food in battle.

It is possible to defeat that one Gear with wings and 500,000 hp. Expect to lose from the hilarious damage you take, over a couple battles.

Don't worry too much about character rotation. Stick with who you like. There will be some sections where one or two of your characters are locked in. But they're pretty manageable even if you haven't used the required section where you got them. Once you reach a certain point your party won't have any required members.

Get used to the differences between gear and personal combat. Mainly storing AP vs. attack levels. As for storing AP for really ridiculous combos. It's rarely worth it, except for boss fights where your target is healing often. In gear combat the attack level denotes which attacks can be followed up with a deathblow. 1-triangle, 2-square, 3-cross, starting an attack with the button associated with a lessor or equal level will allow you to do the associated finisher (assuming your character knows it).

If your gear is at attack level three, take a look at the diagnostics box and looking for the Hyper Mode line. That's the percentage of your character going into over drive for the next three turns if you don't do a deathblow. Same effect as using the System ID(once you get it of course) but any character can do it. Their chances increase if their lower on health. While in hyper mode you have accesses to stronger attacks, and charge 10x the fuel you normally do. May also take less damage but I'm not sure.

Always have each gear equipped with a Frame HP 30. 50 and 90 uses too much fuel, and 10 doesn't repair enough.

There are a lot of things you can miss, but most of them are inconsequential. Noteable exceptions are Ether Doubler which can only be bought early in Nissan, for a ridiculous cost, and the Trader card which when equipped on a character greatly increases the chance of rare drops.

Pay attention to the attack types enemies use. You'll find the enemies in each area focus on a single attack type, like Gel or Seal, etc. They'll often drop protective armour for those types.

Take note of Billy's Ammo, it can be changed. Most importantly the elemental square ones.

When the music turns off, an encounter is about to start. During this time, you can't jump. Keep this in mind for later jumping puzzles.