Oh look, a FFXIV reference!
Hitting everyone at once: Advance Edition
The Arithmetician! A wondeful Job combining the most broken ability se in the whole game of FFT with some of the worst stat multipliers, and growths are also quite bad. But there's appeal in selectively targeting enemies and missing allies, ignoring the most basic aspects of range and positioning.
And so Tactics Advance sought to recover this concept in a less broken and easier to use way; not to mention easier to use as enemy. This resulted in 2 Jobs able to influence every enemy on the battlefield at once, disregarding distance and position.
The first and most simple Job able to hit every enemy at once is the Illusionist. A Magic-based Job share by Humes and No Mous, the Illusionist is an advanced mage blessed with execellent MP and Magic (for Humes, some No Mous Jobs edge them slightly in Magic), good Resistance and bad everything else. The entry cost is steep and the MP cost for their spells is high, but ignoring range and position is not something to scoff at. As for their spells, they have 8 spells in total, one non-elemental and one for each element bar Dark. This makes them the casters most able to hit elemental weaknesses. Now, all this comes at the cost of power: Illusionist spell have lower power than even first-level spells, by about a third. The high Magic of the Illusionist compensates a bit for the lesser power, and the all enemy-targeting nature of the spells makes them easy to use (and aggregate damage is often higher). Other mages will outdamage the Illusionist in single-taget damage though. Illusionist have access to the Absorb MP Reaction ability to recover MP if hit by spells, and with their high Resistance they can get some use from it. They also get Half MP as Support ability, very useful for them with the high Illusion cost (32MP per spell).
In FFTA2 all spells have their cost reduced to 28MP and a bump in power (about on par with 1st level spells), but the need for MP restoration due to the changes in how MP works limits the Illusionist's potential. OTOH there's some interesting combinations with new Jobs, so it's not like the Illusionists are useless now.
The other Job that can target every enemy is the Gadgeteer. This Moogle Job ha actually the best aggregate stat growth in the game, with nice HP, Attak and Magic and great Defense and Resistance; it suffers only from low MP (which frankly aren't much of a problem) and low Speed (which is more of a problem). They use knuckles for weapons and clothes and hats for armor. Between stats and equipment they're suprisingly tanky on both the physical and magical side, and can work as melee unit. But of course we're here for the all targeting, which means their abilities. The Gadgeteer abilities work like this: 6 of them inflict a status, good (Haste, Barrier) or bad (Poison, Darkness, Sleep, Doom). The last 2 are a healing ability and Dispel, respectively. Each ability can target either all allies or all enemies, randomly. This make the Gadgeteer very swingy, because yeah you could buff every ally in the field and get a free victory, but at the same time you caould very well buff every enemy in the field. Reverse this for status, though with immunities and whatnot chances are you won't, say, Sleep every enemy often. Of course there are ways to hedge against abilities going for the wrong side (use only status you don't care about/are immune to, for one) but they're very much a case of high risk, high reward. Gadgeteer also get 2 Reaction abilities, Regenerator (applies Regen if hit) and Damage>MP (damage is applied first to MP, then if they're empty to HP) that helps in making them even tankier.
Tactics A2 doesnt't change things much. Gadgeteers (now Tinkers) gain the new Support ability Ribbon-bearer, that allows male units to use Ribbons equipments. MP Shield (aka Damage>MP) is nerfed by allowing damage in excess to MP to go into HP, unlike in FFT/FFTA where excess damage disappears. Technically now their abilities have a MP cost, but every one costs 8 MP and can be used every turn no problem. The Job is the same otherwise, though a certain escort mission involving a certain Tinker is infamous because the little guy will open with Red Spring for Haste and most likely will hit the opponents, and there goes the mission.
In the sequel we continue this trend of hitting everyone in the bettlefield at once, with the addition of new Jobs that have all-targeting abilities, both for the Nou Mu race.
The first of the new Jobs is the Scholar (no relation to the FFXIV one). Despite the name the Scholar is actually one of the best physical No Mou Jobs, with good Attack and decent Speed. Every other stat is mediocre though, so don't expect to get much mileage out of the Scholar as melee fighter. They can equip hats and light armor, and use tomes as weapons. I guess in Ivalice lifting books makes you as strong as a Fighter. The Scholar's abilities are all Magic-based (despite the Job having only mediocre Magic) and are a mix of buffs/utility with direct damage; they also tend to cost a fair bit. Study reveals the target's held Loot and Items (for stealing) and is the only free ability, Force increases the target's Resilience (so status and debuff have a harder time landing) and Mad Scientist applies a random buff to the target. Then we have the meat of the Job, the all-targeting abilities. Natural Selection hits all characters of the selecter race in the field for ok damage (and can hit the caster if you choose No Mous). The Tome abilities (Eath Dragon, Rime Bolt, thunder Shade, Shadow Shade), finally, hit everyone in the field for elemental damage (respectively Earth, Ice, Lighting and Dark). The inly Support ability they have is Spellbound, tha increases the duration of buffs and debuffs cast on them. The main draw of the Job is the Tome spells, if you target an element your party absorbs (or is immune) and the opponents are neutral or better weak to; this way you get a full-party heal + all-opponents damage in one turn. If you can manage the setup the Tomes are more beneficial than Illusionist spells, and the Scholar can deal Dark damage while the Illusionist can't. OTOH the Illusionist requires less setup, can hit weaknesses with ease (if present) and benefits from Geomancy creating weaknesses (using Geomancy on Tome spells would negate absorbtion). Now in practice both Illusion and Lore are better used as secondary ability set on something like an Alchemist, Black or Time Mage, due to the better Magic growth those Jobs have and the utility Alchemist and Time Mage can bring. Interesting Job, but probably too fussy for most players.
The other new Job that does all-targeting is the Arcanist (also not the FFXIV one). Here we're in more familiar mage territory: low HP, Defenese, Resistance and Speed, ok Magic, great MP (for what it's worth). For equipment again we have standard mage fare: hats, light armor, robes and rods. Abilitie have a net division between the single-target spells and the all-targeting ones. The spells are a bit of a grab bag, they're all returning spells from the previous game or the rest of the FF series: there's Syphon (drain MP), Drain (drain HP), Death (instant KO), Gravity (damge equal to 25% ot the target's current HP) and Graviga (as Gravity, but 50%), all single-target. The multi-target spells are variants that target based on level: there's Level 5 Haste (haste on everyone, allies and enemies, with level multiple of 5), Level 3 Dark (Dark damage to everyone with level multiple of 3) and Level ? Shadowflare (heavy Dark damage to all units with the first digit of their level equal to the caster's), their strongest spell. They ahve the MP Shield Reaction ability (which would make sense with the large max MP pool) and the Pierce Support ability, that allows them to ignore Reflect. Arcanists are weird. Their spells don't really have a theme, like say the Scholar's, because they're a mix of spells that were used by other Jobs (Syphon and Drain were Oracle spells, Death is classically Black Magic, Gravity, Graviga and Haste are very often Time Magic) and some Dark spells that don't really fit in a theme. The spell list is not even coesive like other "versatile" casters, like the Red Mage, Sage or Bishop, because in the end it's only variations of damage with almost randomly choosen targeting (Gravity and Graviga as sigle target? Really?). They can be employed in a similar strategy as the Scholar, so have everyone targettable absorb Dark and go to town with Level ? Shadowflare. There is some merit in this strategy, and level ? Shadowflare is stronger than Shadow Shade Tome (and cheaper), but targeting can be an issue and the same considerations as with the Scholar apply.
We're done here for all-targeting spells, abilities and whatnot. Technically the Blue Mage also has a couple spells of this kind, but it's also the single Job with the most extensive spell list in both games and it deserves its own post