Could “Playing Devil’s Advocate” work as a gist for Oppose?
It’s certainly a short-term form of Oppose. Yet hypothetical opposing and actual opposing must ultimately either diverge or converge.
Is the Oppose character only hypothetically opposing the other character, with actual intent to help that character build a stronger argument?
Or is the Oppose character pretending to hypothetically Oppose the other character, in order to test and find fatal flaws in that character’s argument – which the Oppose character plans to later use to cause the downfall of the other character?
Clearly, “playing devil’s advocate” typically means the former (no-harm-intended argument-testing). But if the Oppose character really is Opposing, then perhaps a better gist for your Oppose trait would be something like “Seeking Gaps in Someone’s Defenses.”