Dark Souls is the 1st stage of The Crazed Cat. Next stage: Deathhawk.
Crazed Cat has 2,400,000 HP, hits for 7,880 in an area every swing, and walks in the moment you scratch a 400,000 HP base — with a Le'boin and a Teacher Bear behind him. You will not out-damage him with an early-game box. You chip him with a Bahamut stack, lose the stack, and then hold him with walls for as long as it takes. This run does exactly that, with no gacha units at all.
The lineup that does it
Macho Cat WALL 
Samba Cat WALL 
Wall Cat WALL 
Dragon Cat DAMAGE 
Drunken Master Cat DAMAGE 
True Valkyrie Cat PUSH 
Crazed Bahamut Cat CHIP Seven slots, no gacha: Macho Cat 22, Samba Cat 20, Wall Cat 21 for the wall; Dragon Cat 20 and Drunken Master Cat 20 for damage from behind it; True Valkyrie 20 and Crazed Bahamut 20 as the heavy hitters. The whole run only ever cycles Wall and Bahamut in the first half, then Macho, Samba and Wall in the second. Drunken Master is the one most players skip because Kung Fu Cat costs Cat Food, and that's a mistake here: Titan-class health, a single knockback, and the second-highest damage you can own before Ubers. Without him, bring another ranged attacker — Medalist Cat or Paris Cat — and one more meatshield to make up for it.
Treasures
Every Empire of Cats treasure at 100% in all three chapters. That isn't decoration on this stage: without the Shield and Sword the walls die faster than the Worker Cat can pay for them, and the Bahamut chip is a third smaller. 'Nearly all Superior' is not the same thing — finish the set before you spend the energy.
Legendary Cat Shieldevery Cat's HP +50% per chapterwalls take a Crazed Cat swing instead of dying to it 
Legendary Cat Swordevery Cat's damage +50% per chapterthe Bahamut chip is what shortens the second half 
Energy Drinkmoney income rate +100% per chapteryou'll spend ten minutes at the wallet cap 
Giant SafeWorker Cat's Wallet Capacity +1,000¢ per chaptera 2,250¢ Bahamut on demand 
Relativity ClockCat recharge times −1 second per chapterWall Cat back before the last one falls SAFE TO SKIPPhilosopher's Stone (XP only) · all treasures →
First half: the Bahamut stack
Only Doges and Snaches come out before the base is touched, and they drop cash. Walls hold them; the Worker Cat climbs; every 2,250¢ goes into another Bahamut. By 2:30 the wallet is pinned at 12,450 and three Bahamuts are standing behind the walls in mid-field; by 4:00 the stack is on the enemy base with it still at full health. Don't hit the base until the stack is as deep as it gets — the cat cannon fires at 4:30 and the base is scratched at about 4:50.
the stack building — Walls and Bahamuts, nothing else · plays here, from that second
He arrives
At 5:00 the base is at 391,200 and Crazed Cat walks out, with a Le'boin and a Teacher Bear behind him and Crocos starting to stream. The Bahamut stack gets its chip damage in — that's the whole point of the first half — and then dies, because it was always going to. Ten seconds later the game says 'Can't deploy any more!', which is fine; you want the field full of walls when the stack goes.
Crazed Cat out, Bahamuts still chipping, unit cap hit · plays here, from that second
Second half: the long hold
From about 5:30 to 8:30 nothing looks like it's happening, and that's the stage. Macho, Samba and Wall on rotation — nothing else, the Bahamut button stays grey — while Dragons and Drunken Masters behind the line take him down a sliver at a time. His range is 240 and his speed is 4, so a wall that dies is replaced before he moves. Watch the wallet, not the field: it sits between 6,000 and 11,000 the whole time because the walls are cheap and the peons keep paying. He dies at about 8:35; the wallet jumps to the cap the second he does.
the hold — three cheap buttons, three minutes · plays here, from that second
After him
Le'boin and Teacher Bear are still there, and now Valkyrie and the Dragon stack go out. The base falls at about 10:15. Watching a full stack of Dragons and Bahamuts die at the five-minute mark feels like losing. It isn't — it's the plan working.
the push — Valkyrie and Dragons on the base · plays here, from that second
THE SHORT VERSIONWalls and Bahamuts until the base; let the stack die on Crazed Cat; then three cheap walls on rotation for three minutes. No gacha needed, but every Empire of Cats treasure is.
The general approach, from the wiki's strategy notes. The guide above walks through one full clear.
Crazed Cat walks in on base hit and the stage is about surviving him — the wiki's answer is a Bahamut stack built on the opening peons and a wall of meatshields.
- Get every Empire of Cats Treasure first (attack, defense, Worker Cat and recharge boosts) and the Upgrade Menu abilities to 20+10.
- Bring five meatshields plus Wall Cat, Dragon Cat and Bahamut; spam only Wall Cat and Bahamut until you are near the enemy base, spending the rest on Worker Cat levels.
- Once near the base, spam everything — meatshields constantly to slow Crazed Cat, attackers (Magica, Dragon, Bahamut) only when the cash is there, because survival comes first.
- Rich Cat skips the early stall, Sniper the Cat holds Crazed Cat at bay (but can make Bahamut miss), and a Cat CPU spams the walls for you at the cost of cash if you brought Paris.
MACHO CAT D Wall in the guide's clear. 
SAMBA CAT D Wall in the guide's clear. 
WALL CAT A Wall in the guide's clear. 
DRAGON CAT B Damage in the guide's clear. 
DRUNKEN MASTER CAT C Damage in the guide's clear. 
TRUE VALKYRIE CAT A Push in the guide's clear. 
CRAZED BAHAMUT CAT A Chip in the guide's clear. 
MAGICA CAT B Magica Cat - Capable of weakening Crazed Cat from somewhat long range, which can help other units, such as Wall Cat or Dragon Cat, survive more hits. They are outranged by Teacher Bear and Le'boin, so watch out for that. 
CAMERAMAN CAT B Cameraman Cat - While you'd likely have to go out of your way to have her by now, Cameraman Cat is a great attacker here. She outranges Crazed Cat, is spammable, and has enough health to survive an attack from Crazed Cat, even without activating her Survive ability. She needs her True Form to provide any value though. 
DRILLER CAT A Driller Cat - While it's not too likely you have them yet, if you do, they can be an excellent crowd-controller here, able to weaken Crazed Cat by a huge amount. Their weaken doesn't have full uptime, but that can be fixed by stacking them on peons at the beginning of the stage. They have even higher range than Bahamut 
URURUN WOLF B Ururun Wolf - While it's generally advised to complete this stage before getting Ururun, in the case you don't, Ururun provides a great mix of both attack and defense. Her knockback can push Crazed Cat back behind the Teacher Bears and Le'boins, allowing your other units to land hits and kill them, but her knockback ca 
PRISONER CAT B Prisoner Cat - If you get Prisoner, this stage is almost free. Stack them up with the beginning Doges and pair him up with 5 meatshields to hold off Crazed Cat. He would snipe the backliners and the base before Crazed Cat can do anything. Crazed Cat is Traitless. Anti-Traitless units take less damage and deal more.
HITMAN CAT A Hitman Cat: Deals massive damage to Traitless enemies Also fits “Clear the crowd.” 
LONE CAT AND KITTEN A 100% KB + Freeze + Resist vs Traitless. Also fits “Out-range Crazed Cat.” DRILLER CAT A 100% Weakens Traitless to 10% and (True) Strong vs Traitless. Also fits “Out-range Crazed Cat.” 
D'ARKTANYAN S Strong Against Traitless on a Long-Distance area attack — answers the many Traitless bosses. Also fits “Out-range Crazed Cat.” 
JAGANDO JR. A Lord of Ruin Jagando Jr.: Strong against Traitless enemies (Deals 1.5x damage, only takes 1/2 damage) Also fits “Clear the crowd.” Crazed Cat reaches 240 range. Units that out-range it can chip safely without taking hits.
GROSS CAT A Range 350 — fires from beyond its 240. 
MASTER URIL A Range 405 — fires from beyond its 240. Also fits “Clear the crowd.” 
SALON CAT S Range 350 — fires from beyond its 240. Also fits “Clear the crowd.” 
NERD CAT A Range 1200 — fires from beyond its 240. Also fits “Clear the crowd.” 
MIGHTY REKON KORPS S Range 470 — fires from beyond its 240. Also fits “Burst the boss down.” Crazed Cat has a deep HP pool (2,400,000+ even before stage magnification). Heavy single-target burst shortens the fight.
BAHAMUT CAT S Huge multi-hit burst — a story-unlock powerhouse that deletes tanky enemies. MIGHTY REKON KORPS S Among the highest single-hit Area damage available. Also fits “Out-range Crazed Cat.” 
GAIA THE CREATOR S Long-Distance multi-hit with Insane Damage — a generalist wall-cracker. Also fits “Out-range Crazed Cat.” 
CRAZED MONEKO A Big crit burst against tanky/Metal targets. 
CHILD OF DESTINY PHONO S Big Multi-Hit Massive-Damage bursts from safety. Also fits “Out-range Crazed Cat.” 6 enemy types stack up here. Area attackers hit the whole push at once instead of one unit at a time.
URURUN WOLF A Area attacks hit everything in range. Also fits “Out-range Crazed Cat.” SALON CAT S Hits whole crowds, and is Weaken-immune so it keeps firing through Weaken stages. Also fits “Out-range Crazed Cat.” NERD CAT A Evolved/True hit groups over a Long Distance band. Also fits “Out-range Crazed Cat.” D'ARKTANYAN S Area damage means it punishes grouped Traitless enemies at once. Also fits “Counter Traitless.” 
ACTRESS CAT B Hits multiple enemies at once for budget crowd damage. Also fits “Out-range Crazed Cat.” 
The castle you destroy to clear the stage.