I’m gonna compare the Koopalings and characters from My Little Pony.
Ludwig- Twilight Sparkle
They are both smart and like reading books.
Lemmy- Pinkie Pie
They are both happy and childish. AND they both like parties and FUN!
Roy- Rainbow Dash
They both are cocky and competitive. They just both have a similar personality. And are both physically strong.
They both like animals. (That is all.)
They are both girly and overdramatic.
They are both physically strong.
(Roy just fits Rainbow Dash better.)
Bowser Jr.- Diamond Tiara
They are both spoiled.