Stone (status effect)
From the Super Mario Wiki
Stone is a status effect in the game Paper Mario. Mario gains this status when he uses a Stone Cap. The animation for the Stone status depicts him crouched in his defense position. While in Stone form, he is impervious to enemy attacks, but also prevents Mario from moving, leaving only his partner to attack.
While wearing the Feeling Fine Badge, Stone will always end on Mario's next turn. Whether this is a glitch or not is currently unknown.
The status effect returns in Mario + Rabbids Kingdom Battle, where it prevents inflicted characters from acting at all for one turn.