Littlest Pet Shop is fun for the young.
My daughter is 4/5 and has spent many hours of fun playing this game.
Littlest Pet Shop requires a little bit of reading skills. A parent should play along with their child a little so they will know the basics; after that they are good to figure out the rest of the game.
You basically have a pet that you control and take them to different play areas and collect coins. Some mini-games require you to hit the "A" button repeatedly, others to shake the Wii-mote up and down or side to side. The mini-games involve pretty basic things that children can pick up and improve their co-ordination with. As you progress you can buy new pets, clothes, or toys with the coins you have collected.
All in all this is a great relaxing game for children who aren't yet able to play the more intense games that older brothers and sisters can.