Champ

n.capable, kindplayful

Meaning 1

A champion or winner, especially in sport or competition.

Reach for it when using a short, informal title for someone who has won

The regional chess champ stayed to analyze the final position with her opponent.

everyday
champion
a recognized winner needs the standard full word
not when Champion can also mean advocate, so context must establish competition.
everyday
winner
the result matters more than status or affection
not when Winner is neutral and lacks champ's admiring, informal tone.
formal
titleholder
the person currently holds an official competitive title
not when A winner can be a champ without holding an ongoing title.

A person admired for handling something especially well.

Reach for it when offering warm, informal praise for capability or resilience

You were a champ about changing rooms at such short notice.

playful
ace
exceptional skill deserves breezy informal praise
not when Ace sounds dated in some regions and may reduce a broad contribution to talent.
everyday
hero
the person's action deserves unusually strong admiration
not when Hero is inflated for routine competence and may embarrass the recipient.
warm
star
someone's excellent performance stands out
not when Star can imply attention or celebrity rather than dependable handling of difficulty.
warm
trooper
good humor and endurance through discomfort are central
not when Trooper praises endurance and can normalize burdens that should be removed.

reigning champ
The reigning champ congratulated the new winner before leaving the court.
local champ
The local champ runs a free practice session each month.
like a champ
Mina handled the delayed connection like a champ.
defending champ
The defending champ welcomed the new finalists before play began.

The definition and the example on this page are written here. The dictionaries above ground which meaning is being described, not the wording.