First, level up Charmeleon to 28, when it learns Flame Burst. It might be kinda tedious, considering the level cap, but it will pay off, since it's far more stronger than Fire Fang. Make sure to ev train it in special attack as much as possible. This is important, because you'll need as much hp as possible for when Cradily comes out, and you need to be able to ohko every single one of her pokemon. Also, train your pokemon until they're just below level 26, so they can level up in battle without disobeying you. Lastly, get 5 more Noibat. That said...
The first strategy is based on the premise that Charmeleon will not have any problem taking down any of her pokemon, specially if it levels up during the battle. Since most of her team has a super effective move, there's a chance she'll send out Cottonee, Cacnea or Ferroseed before Cradily, so you would probably have taken down 4 of her pokemon before Cradily comes out. However, if it does come out first, you would have to use your 5 Noibat to chip it down to at least 80 hp. They will most definitely die in 1 hit, so you need to rely on supersonic and screech hax (yep) to chip it down enough, just so Charmeleon is able to 2hko it with dragon rage. After that, you just sweep with Blaze boosted Flame Burst, and whatever remains of your Noibat squad.
However, there's an alternative strategy. Teach Charmeleon substitute, and use it on turn one, since you probably have a free turn with Maractus spamming spikes. With the substitute, you have 3 turns to hit it with dragon rage. Cradily can never ohko Charmeleon with 75% heath, as long as you have a minimum hp and defense stat of 73 and 38, respectively (you would have to ev train to compensate). When that thing goes down, you have either 5 other Noibat to clean up, or a Charmeleon in Blaze to sweep trough the rest of her team with Flame Burst.