when we had a lot of cats and the occasional intruder cat, "duels" between one of ours and one intruder were most common. meet on neutral territory, hurl insults, maybe there's an attack but maybe not. and only after sufficient insults.

this was a specifically male behavior, too. we got a young female cat, and the 2 older males were horrified when she came and jumped their opponent. she was very no holds barred, get off my lawn, don't mess with my guys. a different time, a different young female cat was equally willing to jump in swinging claws and skip the insults.

typically the other male cats would be hanging around, observing and jumping in only if things moved from neutral ground to their territory.