Plot: Sherman Grant, junior detective, must protect a comatose Batman from the Penguin using Home Alone tactics.
That is to say, episodes with the Penguin are almost never about the Penguin. They are about someone else, like for example a boy caught between him and Batman. There's only so much time to establish a new character, and if you're focusing on a new ally, then the villain has to be someone already established to be a threat. But any of Batman's other established villains would warp the story around them. On the other hand, the Penguin, for all his affectations, is very direct, he's a sane man, who wants money, and is willing to kill for it. Established, recognizable threat, but not one that requires too much attention.
That is NOT to say the Penguin is boring or uninteresting. On the contrary, he's one of the more well-rounded villains Batman has (sorry). Just as Poison Ivy uses both evil botany and seduction, the Penguin has two unrelated gimmicks: his affinity for birds (he uses a vulture to steal an egg) and his trick umbrella (from which he draws infinite weapons). Design-wise, this Penguin draws a lot from Batman Returns, a general egg shape and flipper-hands.
One element that's in the story bible that I believe never made it into the show is that he still lives with his mother, and tries desperately to keep her from finding out he's actually a criminal. When he goes to jail, for example, he explains he's off on a trip to South America for the Audubon Society and will be out of contact for a few months. And that's the heart of the character, the infinite distance between the schlub he is and the man he pretends to be.
What were we talking about again? Oh yeah, this episode, which isn't really about the Penguin at all. This episode is about Sherman Grant, who is basically Encyclopedia Brown. He has his Sally, in tomboy and bodyguard Roberta, and even his own Bug Meaney, two of them, actually, named Frank and Nick. What he doesn't have is a police detective father (or any father) to bring home cases or any neighborhood clients. But he's curious, and he knows enough to recognize a South American vulture and know it means something mysterious is happening, which is a good start.
Once again, we come back to Batman being an inspiration to children, giving them the confidence to take on bullies, and then supervillains. Sherman needs Roberta to save him from Nick and Frank at the beginning, but is able to yell at them when he needs to protect the Batmobile. And he leads the charge against the Penguin, even if it only just barely slows the Penguin down.
I wish he was a little smarter, actually. He only figures out how to turn on the Batmobile by button mashing (great security there, Bruce) and it's Roberta who figures out how to work the petals and steer at the same time. His reasoning for not calling the cops (they'd unmask Batman) is plausible, but ultimately foolish, and he doesn't decipher what Batman wants from his car until after Frank stumbles upon the pills clearly labelled "Antitoxin." Maybe I'm asking too much of 11 year olds, or as a world weary Roberta says, "Men."
One interesting line is that Sherman not only recognizes the Penguin on sight and has a Joker poster in his crime basement, he also knows about the Batcave. It's hard to see, from the episodes we've seen so far, how anyone other than Bruce, Alfred, and Dick would know anything about Batman having a secret crime fighting base, let alone one in a cave. The only other person we've seen in the cave is Man-Bat, so maybe Kirk Langstrom talked after he returned to humanity. Or maybe Batman just cannot shut up about his sweet crib. Who knows? I certainly don't.
This is also the fourth time someone has tried to gas Batman (Fear, Laughing, Tear, and I guess Poison). One would think he'd learn to just keep the gasmask on.
So, an enjoyable romp about kids learning to fight crime. All in all, good fun.