I’ve beaten Dragon Quest Heroes: Rocket Slime on the DS a couple of times which I rarely do, it’s just a super cozy and cute game with a simple and fun gameplay loop. Short? I’m pretty sure it’s below 10 hours, possibly even shorter like 4-5. Charming? Come on DQ slimes are extra charming!

Ghost Trick is fantastic.

Also, Liberation Maiden was extremely short, but pretty good.

The Rub Rabbits and Feel the Magic XY/XX ooze charm, they’re great

Final Fantasy Theatrhythm is good for short bursts, it’s kind of an infinite games

Code of Princess is a fairly short Beat’em up / RPG hybrid. I don’t remember the full game length, but each stage was short and the game was somewhat short overall.

The Regular Show platformer is quite nice IMO. It’s some basic platforming action, but if you like the show, you will like the game, too. Also, superb soundtrack made by Jake Kaufman (Virt).

Sadly most of the really short games I can think of were download-only games, so they are lost now. But if you don’t care, I’d definitely recommend the already mentioned Attack of the Friday Monsters. I really liked Ikachan which is very short (under an hour), it was made by the same person who made Cave Story, I think. I could be wrong about that. Bloody Vampire also was a nice and simple Metroidvania style game.

As for actual retail games, I guess the Kirby platformer games would fit that description. The 3DS ones, especially Triple Deluxe, are some of the better ones in the series. The Mario & Donkey Kong games are also rather short, but really nice puzzle games.

I’d recommend you the Animal Crossing games for both DS and 3DS.

Also I don’t know if it fits entirely in the charming area but check out Ace Attorney saga.

Also if you are a fan of Evangelion there is a game that looks quite simple but it is a big what if of Evangelion wholesome AF, I don’t recall its name right now.