No, that is FALSE! I got Mametchi twice and their growths are:
Gen 11: Tails the Mametchi!
Teletchi - Kuchitamatchi - Young Mametchi - Mametchi
Gen 13 - Roget the Mametchi!
Shiroteletchi - Kuchitamatchi - Young Mametchi - Mametchi
So for me I get Kuchitamatchi (By leaving it with four poops...