The main singer sounds like he has Down syndrome

Fire Emblem Engage - Bloom in the Breeze (Blossom)

Shin Megami Tensei IV OST - Shibuya Underground District -

Pokemon Advance Generation: Battle Frontier Season 09 
New Single Opening S9
Battle Frontier / Batoru Furontia by Akina Takaya

Persona 5 Dancing Star Night / Dancing in Starlight - Price

From the OST of Persona 5 Dancing Star Night / Dancing in Starlight.