I just dont now, I has a OP loop run (sanguine bond + Isaac fork) and everthing was fine, a Little hard on it's all mine, but posible

Ark is imposible

Is absurd, the frosty's just totally ruin the deffensive, and the abusive amount of monsters are imposible to fight back whit the aucense of hearths

I tried to do it on a not-loop run and i lose in it's all mine II...

I dont have idea how to beat the game without the Little C.H.A.D, specially the ark

A good combo is ghost baby, dimensional baby, bob's brain to disable mulligans and those who eat you a baby and leave and the ball of bandages with this obviously (blood bond + Isaac fork

Doing it on a loop is harder even if you have every single advantage, Ark 2-3 is no joke. 

(I miraculously completed it on loop 4 on my first save file and in an hour completed it on a non-loop run on my second save file with no sweat)

Fishing material (you can complete first two floors just by using the base four babies so the focus is on Ark 2-3):

• Lil Loki is a solid pick since it can not be stolen by hands.
• Bob's brain is essential pretty much: against mulligans, whales and unexpected breaches.
• Deserters can be nice at the start of Ark 2-3 (and OP before that) since only 2 of them cover every line and destroy basic mobs with AOE;
• Blue Candle can empower Deserters with blue flame and they spread that blue flame to each other, so they might be more useful (this combo alone can carry you up to Ark 2 even on a loop; you probably do not even need the combo if you are not looping).
• Imp is OP if you are lucky to get one from Mystery Gift since it costs 0.
• Ghost baby is strong, but as any other fire power you are likely to lose them by the last wave due to hands.
• Blanket and/or Book of Shadows can help secure some fire power.
• Sanguine Bond is really good to place cheap spikes with Cube of Meat;
• Isaac's Fork is OP here to have some hearts going, but not essential, Red Shovel can be also of help since you do not usually want to have blow up material near the entrance and it saves you some hearts if you are removing Cube of Meat.
• Chargers can win you the last wave of Ark 3, just save them before that.
• Salvation effectively gives you free chargers so you can be more flexible with your defense on last wave.
• Glowing Hour Glass is all round best defensive and disaster-preventive active item; you can make enemies walk over your spikes twice, remove a sneaky bastard on that one line away from your charger or prevent an explosion, etc.
• The Black Bean is cheap and flexible source of AOE damage, can be helpful to weaken waves while feeding whales with bob's brain or placing Sanguine Bond's spikes in the process.
• Notched Axe can help you destroy "stoney bois". 
• Poke Go is really good, basically a free utility on cooldown. 

One timers like Snowball and BFF are a waste of space and hearts, do not use them.

TLDR: 

On a fresh run fish for:  Lil Loki, Imp, Deserter + Blue Candle, Ghost baby, Blanket, Book of Shadows, Sanguine Bond + Isaac's Fork + Red Shovel, Salvation, Glowing Hour Glass, The Black Bean, Notched Axe, Poke Go. Take Bob's brain.  And avoid Snowball and BFF.

i recommend doing it on the first go since ark gets incredibly difficult on loops, all of blue room and most of mines can be done with brother bobby alone, just about 80% of every other attacking baby is useless in comparison since they're too expensive and not cost effective except for: lil loki, harlequin baby, spike baby (for isaac's fork synergy) and deserter, peeping might be good now since the rework but i have yet to try him out; as for items be on the lookout for: isaac's fork, sanguine bond, frosty mint, black/brown bean, present (for the chance to get imp since it's the only way to get it) and safety blanket; as for active items try to get a run with either kidney bean, blue candle, glowing hourglass, telepathy for dummies or monster manual, sacrificial altar can be pretty powerful too but so would moving box, but if you ask me i'd say the go to actives are glowing hourglass and kidney bean, with glowing hourglass you can counter the mom hands and with kidney bean you can charm the frosties to fight on your side for basically the rest of the level.

Thanks for the help, first, peeping baby dont work, is good on the first monsters (if you have scoolbag or moving box, especially the last one, is good idea take one with you), but weak on waves as a lot of firepower is losed on a monster that already die

The imp is good, but you need luck, I haven't try bob's brain, so is a good moment to do it. I gonna try to unlock the blanket first (as the only unlocks that I dont have is the blanket and the double C.H.A.D)

I never think on use lil Loki, so time to try it

I wanna ask now, I think on a strategy, but wanna now if is a good idea

Play the game like the "limited edition" challenge

Wiz baby

Acid baby

Fart baby

Ball of bandages

Use the ball of bandages and fart babys to keep enemies on the 1, 2, 5 and 6 lines, and leave the wiz babys do the work, using the acid baby to buff multiple Wiz babys with power or speed up pills