Character powers/ratings- This is for settings where they have their vanilla abilities.
Note: This is my opinion only. I am revising this to explain why you should be happy to get each character. What I have learned over playing this rando since the start is that each character is powerful, each has their uses. Some may be more generally useful, some may be situational at best, but they all have times where they can shine. So I am doing away with tiers. They are in some sort of order of how happy I am to get them, but that is not indicative of their potential.
He opens 5 checks (Gau’s Manor is free), and the Floating Continent is 3 checks in one spot. In addition he has throw. Throw is really good. Scrolls are essentially half powered rods (due to being impacted by magic defense), at about a fifth the price. They remain powerful through the game, and can hit three elements. Thrown weapons (but not scrolls) ignore defense, and use the battle power of the item (so Ragnarok will hit harder than a dirk). They also take on the element of the weapon thrown.
I recommend getting shuriken and elemental scrolls as they are helpful as either a generically powerful non elemental attack, or as AOE elemental attacks. Scrolls are really good for grind fights like Water scrolls on the Burning House or bolt edges on commandos at the Imperial Base.
It is also possible to grab a bunch of powerful weapons to throw, such as Snipers or other high battle power weapons from shops. I would reserve those for tough fights.
Opens up 5 checks. (I count Magitek Factory as three).
Good base magic stat.
Depending on setting she can usually equip most of the best equipment in the game, namely the top swords and Minerva’s. She is a generally solid and valuable character. Even if she were a blank character with nothing but the checks she opens she is still great.
Terra opens 5 checks. Imperial base/Sealed Cave are great for treasure looting.
Morph is stupidly powerful. I AM SAYING THIS AGAIN! IT IS STUPIDLY POWERFUL. It doubles your magic attack power. This counts for spells, as well as breaking rods/shields. Really powerful. Since WC usually has increased magic point gain, it will be possible to use this a lot more often than you could in the vanilla game.
Good base magic stat
Depending on setting she can usually equip most of the best equipment in the game, namely the top swords and Minerva’s.
I was not a fan of Sword tech. I want to call attention to this statement. I was wrong. With fast Swdtech it's really good. REALLY. GOOD. If you get him early, go to his dream sequence, it will unlock all of the techs. Then you can use 8 to beat most trash mobs in the game with one ability. He makes grinding much easier. He can also easily break the damage cap with Quadra Slice and enough levels/gear.
He’s really really slow. Other than that decent stats, a really good set of checks, and Swdtech is deceptively good.
Opens 5 checks. Collapsing House is free, Imperial Camp and Barren Falls are quick trips to their fights. Phantom Train you can check the caboose and see the reward and decide to reset out if you want. Mt Koltz is… another check.
If you can get Bum Rush he is really strong. Even without Bum Rush, get a few levels, and Aura Beam/Fire Dance are powerful options. Most of his good blitzes (Aura bolt, and Bum Rush) go off his magic stat. Pummel also ignores defense which is important for things like Tritoch.
Setzer opens two checks and a half. Kohlingen Inn is free which is a nice bonus. Darryl’s tomb is not terribly difficult either. Search The Skies lets you find Doom Gaze instantly, but you can find it normally, so a half check.
Slots, 7-flush in particular is good non-elemental AOE damage if you can reliably hit it. He can also usually equip fixed dice which is one of the most powerful weapons in the game.
Has the highest base magic stat in the game. If you have good spells for her to learn, she is the most powerful magic user without any esper buffs. In particular if you do not find any magic power + espers, she will be your second strongest magic user, behind a morphed Terra.
Esper Mountain is an easy run to the boss fight. Owzer’s Mansion used to be a top tier grind spot, but with shuffled fixed encounters it is less guaranteed, but still solid.
With the right rages he is super powerful. Without good rages he just meh. You can check out the tracker made by Raitzeno which also includes a tab about Gau’s rages. I copied the best 16 rages in the image below. These are not the only usable rages, just the best ones. Serpent Trench is a decent check, gives you a few battles for some XP. If you find dried meat his other check is super fast as well.
When Gau is allowed to equip weapons, he gets VERY strong very fast. His rages are designed with the idea that Gau does not have a weapon. So getting him a good weapon and an offering and using Stray Cat, or Gold Bear and you will see DUMB numbers. Yes Catscratch works with offering. Yes its silly. It also works with Fixed Dice. Yes. That is REAL GOOD.
Below are the best rages. Others one that can get you through in a pinch: Templar has Fire 2, Behemoth is Meteor, Slam Dancer is Ice 2.
Edgar opens three checks. You can do them all in one trip to WoR Figaro. Go through the south figaro cave, do the Tentacles fights. Run up to the Throne Room, then do the Ancient Castle.
He does give you half priced shops in Figaro Castle and in World of Ruin South Figaro (for....reasons?). This can be really taken advantage of if there are rods/super balls/ elixirs in these shops.
Tools is another ability that I have underrated. Drill ignores defense. Flash uses his magic stat for spread damage. Chainsaw can cause instant death on some targets. Air Anchor also triggers instant death (good for some of the enemies in the final Kefka fight even).
Dances are unreliable, but decent stats overall. If you learn what the possibilities of each dance are you can take advantage of them. It takes some knowledge, and some luck. The check is easy, but a bit time consuming. If you have not looted the Lone wolf chests yet its even better.
Earth Blues has Landslide, which is effectively Flare. Really good early, but mildly unreliable. Mog makes a great dragoon since he can equip all the spears. He also has a really solid Magic stat.
Grand Train, quasar, clean sweep, aqua rake, and aero are powerful spells. The first two retain their usefulness through the game, the others tend to drop off a bit. All of these are good for clearing monster packs. Otherwise he's just a decent magic user. Strago’s usefulness really depends on what lores you have access to.
His checks are a mixed bag. Burning house can be a fantastic grind spot depending on the encounters there. Fanatics tower is long, and the boss may be a challenge. Ebot’s rock is annoying RNG fest.
Can do a bit of anything, but his stats are low.
Gogo can basically fit any role you need him to. If you have Bum Rush, you now have a second user. If you have a good selection of magic, now you have another user. He is held back by the fact that you cannot use espers to raise his stats. But if he can equip decent gear he can really make up for that.
The Zone Eater check is fine, the green men are annoying and the crushing ceiling can game over you. But as long as you have warp/warp stone it is a fairly quick check to grab.
Can usually equip the best swords and gear. I am unimpressed with steal. He does give you a free check in the WoR Weapon house, and while you are there gets you a cursed shield which depending on your settings may be worthwhile trying to uncurse.
WoR Narshe is a good check, Phenix Cave has lots of treasures in it. Tunnel Armor spot is also fairly quick to do.
If I get him early I do his WoR Narshe checks immediately to see if the cursed shield is worth uncursing.
He has his uses! Assuming he has his base gear he can solo Tritoch. His body slam ignores defense which is really good as well. Rage ring and Blizzard orb open up the possibilities a bit. If you can change his gear you can put better weapons on him, which will get you a lot of mileage. You can also strip him of the muffler, which is also great.
The check is behind two bosses (Tritoch spot and the Sasquatch fight). Its fine, but near the bottom of the list for me in terms of how much I want to do that check.