They are young. And enjoy Pokemon.
No PS3. I would buy them a Wii.
I have problems with that kind of thinking.
When I started playing games, they were hard. They weren't "kid friendly". You had to sweat your way through the game, learn the patterns of the enemies and sometimes even the entire levels by heart to succeed...
There were no "easy modes", no casual games, and the games hardly ever took your hand through the levels. You had to figure it all out by yourself...
Yet kids still had a blast.
Heck, I was 9 when I first played Final Fantasy, in 1989. I didn't understand everything that was going on, I learned a lot of the game's mechanics through trials and errors, but I was having a blast doing it. Enough that it became my most beloved game franchise. Before that, I was playing games like Maniac Mansion on the C64, hardly the most simple game for a non native english person...
So yeah, kids can learn pretty fast. As long as they understand the language, the game can and most likely will grow on them.