I named my Shiny Shroomish あきし (Akishi), which can be translated as "Autumn warrior". It is a suitable name for a male shiny Shroomish because it has autumnal colours and is a mushroom, which can be associated with autumn. He has a Sassy nature and his ability is Poison Heal, which is a good ability to have in order to confuse opponents with a poisoned Pokémon healing itself.
Also, he has a perfect HP IV thanks to his Korean Shroomish mother (his father is my own (Japanese) Chikorita who has a Serious nature, which is in accordance with the rules I have set on the first day of the Shiny Pokémon Week). After the long stretched out time that passed in order to get a shiny, I have taken a break from Pokémon breeding at the moment.