>>56682671it has a dex entry stating the tied knot at its neck helps it store power in its belly that would otherwise release (like a balloon losing air when not tied off), the leg is like the string of the balloon.
but some people also say its based on a punching bag (learns counter) or punching glove (flying fighting typing and japanese name "karamingo"). its so unclear what its supposed to be because the design is too bad at conveying that.
I personally think the silly balloon bird idea could have been cool if it was actually applied to the design, imagine it flying by thrusting out air and having a floaty wobbly nature, sucking in air before an attack for a bigger fist effect. theres so much you can do with that but none of it is actually put out there