5 Reason because Pokémon isn´t for kids:
1º: there are a lot of parameters in eah pokémon(IVS and EVS)
2º: the types´ table is very difficult for a kid.
3º: the breeding is bored and it can last weeks
4º: there are a lot of attacks with various effects
5º:Is difficult the creation of a equilibrated team

Photo link:
https://lh3.googleusercontent.com/-g_kmEp0Ss6M/VcHy6DIfacI/AAAAAAAAESc/MRP_BXq9ggc/w960-h800/Blue%2BPokeball_161.jpg

Sorry for my english :p