Joubush has a great attack stat, handy dual stab in steel and grass, and solid speed. A diverse physical movepool ensures it's ability to fit on many teams and generate unpredictability. It is solely a sweeper, but how it sweeps should be decided by your team. Need something to destroy walls quickly? Choice Band is your set. Need to revenge kill many 'Mons? Choice Scarf has your back. Looking to stall break? Swords Dance will destroy the stallers.
However, this knightly avian is hardly invincible. It has rather average defenses and most super-effective hiuts or high-powered stab will hurt it extremely badly. Add prior damage from spikes and stealth rocks, and this can be KOed easily.
Definitely cover Joubush's weaknesses and you'll have a solid team-member.
Choice Band
Adamant/Jolly
EVs: 252 ATK, 252 SPD, 4 hp
Leaf Blade/Power Whip
Iron Head/Iron Lance
Drill Run
Superpower
This is Joubush's best coverage. Drill run defeats fire types, which resist it's stab, and Superpower defeats steel types that would otherwise wall it.
With this moveset, there are precious few safe switch-in. I have calced Every 'Mon and they either have too little raw stats (Claspirito, Beluga), a weakness to one of it's coverage (Seradder, Diablode, Fuzard) no way to hit it back meaningfully (Trunklift) or any combination of the three (Venohm). The only thing that can be safe from Joubush are, fittingly, fire types that can annihilate Joubush with their fire stab. Ripodictya take little from all four of these moves so long as it had a little bulk (Max HP), and Joubush doesn't know a single move to cover it, while Ripodictya can wipe it out with flamethrower/fire blast. Suzaestial also take little-to nothing with some kind of bulk investment, and takes care of Joubush in the same way.
The problems with these two counters? They're x4 weak to stealth rocks and both slower than Joubush unless scarfed. If Stealth rocks are up, their ability to wall Joubush is severely hampered. Luckily, they both can learn a recovery move in roost, but their SR weakness and lower speed means they cannot switch into Joubush safely most of the time.
In summary, choice band Joubush is a devastating force capable of immediately threatening everything in the game, while it can be dispatched of with strong moves.

Choice Scarf
Adamant/Jolly
EVs: 252 ATK, 252 SPD, 4 SDF
Power Whip
Iron Lance
Drill Run
Pursuit
This set is THE revenge killer. It has near-perfect coverage, as previously mentioned, and can outspeed everything bar faster scarfers. You'll want to use Iron Lance & Powerwhip over their higher-accuracy counter-parts due to the weakened power due to the loss of Choice Band. Pursuit over superpower, as drill run covers fire and steel types anyways, as it allows you to catch Pokemon that might fear you and switch out. Otherwise, this set runs near identically to the choice band set except your goal is to revenge kill fast and powerful Pokemon like Darspirita, or pursuit trap Pokemon like Atavism, who would outspeed you if you didn't have a choice scarf.

Swords Dance
Jolly/Adamant (Life Orb/Leftovers)
EVs: 252 ATK, 252 SPD, 4 SDF
-Swords Dance
-Iron Lance/Iron Head
-Power Whip/Leaf Blade
-Drill Run
This set once again has many of the same moves as those above, except superpower is swapped out for swords dance. This set is especially effective against bulkier teams, as it can set up and heavily damage most Pokemon, is cannot be toxic-ed, and wouldn't stay in on something that could burn it anyways. Just be aware that you can still be outspeed by Pokemon such as Darspirita and Atavism, who can KO you if you're weakened (such as being hit while setting up, or from hazard damage, or priority). The choice between life orb and leftovers is the difference between power and longevity. Lifeorb bringing the power, and leftovers bringing the longevity.

Life Orb
Jolly/Adamant
EVs: 252 ATK, 252 SPD, 4 SDF
-Synthesis
-Iron Lance/Iron Head
-Power Whip/Leaf Blade
-Drill Run
This set lies somewhere between the power of the choice sets, and the freedom of switching moves the SD set grants. Synthesis is there over SD for longevity, as being worn down by life orb and Iron Lance recoil(if you're not running Iron Head) is just too much. You can synthesis on any Pokemon who would fear any of your attacks, or on walls who can't do much damage to you.

Other Options
Joubush has a decent base 80 special attacker, a special movepool that just makes the cut, and a way to raise it's special attack. However, a special Joubush is still vastly inferior to it's physical sets, bringing more immediate and impact with its power. Zen Headbutt can be run on the physical sets to harm poison types, but drill run already does this as well as covers against fire and steel, and Iron lance hits most poison types for the same neutral damage anyways. A substitute swords dance set could be run to avoid getting burned, paralyzed, or put to sleep, but the loss of a coverage move or STAB attack really opens it up to being walled, and it outspeeds most mons that would dish out these statuses anyways. Low kick is an option instead of superpower as it doesn't lower any stats, and there are some heavy Pokemon it can hit super-effectively (Trunklift) but superpower just brings more power to the table in general, and so is superior to low kick. A Defensive set could be run, with any combination of Toxic, Synthesis, attacking moves, Resttalk, or even Iron Defense. Double Team and Swagger, while utterly relying on chance, can be used if you're into that sort of thing.

Dragablo is quite an imposing fire type, boasting a beefy attack stat, decent defenses, yet average speed. It's special defence in particular isn't very good. However, like all of Ratty's starters it's movepool is far from shallow like most fire-types, and gives it plenty of options.

Choice Specs
Modest
EVs: 252 Spa, 248 hp, 8 Sdf
-Fire Blast
-Dark Pulse
-Hidden Power Grass
-Earthquake
It's amazing base 130 special attack stat makes a choice specs set the first thing to come to mind, and with good reason. While it's not fast enough to outspeed many Pokemon, it can certainly be faster than most walls, and destroy them with it's high-powered stab and some coverage moves. Due to its use as a wallbreaker, running speed on it isn't necessary or effective, as most things you would want to outspeed are too fast even with investment, such as Claspirito(who gains Hydro Pump from a Pre-Evolution) and Quodash. You also don't need speed investment to outspeed the walls you want to anyways, so running bulk is almost always the better option to allow you to not take much damage from the attacks walls might throw out. Fire Blast and Dark Pulse destroy anything that doesn't resist them, and few Pokemon resist both. Earthquake takes good care of opposing fire types, even if you have poor attack thanks to being modest,