second
bottleholder
contester
monomachist
coparticipant
contender
hold the ring
agonist
encounterer
go to bat
assertor
participant
competitor
coquetter
Hellanodic
combater
Law of Conservation of Ninjutsu
gamesman
opponent
gunfight
play
alliancer
meet
compete
take on
coopetitor
agonistarch
encounter
swordplayer
outduel
competitorship
mano a mano
stager
presentation
old hand
dueling
adjunct
oldtimer
battle it out
veteran
warhorse
old-timer
duel
old stager
champion
challenger
fighter
adversary
overleveled
coruler
racketeer
swordfight
logroller
interactor
interactant
forefighter
dueler
sport
duelist
duellist
dueller
event
oppugner
sidekick
batman
stickler
measure swords with someone
second fiddle
game
cowinner
shield
uphold
maintain
foiler
counterpetitioner
ruck
tilter
with friends like these who needs enemies
tie
counterplayer
handler
gameplayer
gomer
kiss-ass
matched
concurrent
cross swords
gamesplayer
over-the-board
power gamer
vice
objurgator
aide
kemper
den mother
to find a better fitting word. Finally, thanks to ChatGPT, the overall results have been greatly improved.