This is hardly a bug.
That Wake was clearly holding specs.
Forcing choiced mons to perform an extra move right before they attack cancels whatever move they were going to use that turn unless it's coincidentally the same move as the extra one they were given. You can see this in standard play by having a mon outspeed a choiced Oricorio and click a dancing move. It'll proc dancer and revoke their rights to whatever move they wanted to fire that turn.
Note: This only causes them to fail on the specific turn this happens. They don't have to struggle or use anything unwanted on the next one,
unless they have that move in their moveset already (Something that won't come up in Trademarked).
Skill Swap has no other use as a Trademark due to the "once a turn" Trademark rule. People using Skill Swap ™ are only doing so because they know about this interaction. It serves the specific purpose of letting them get one free switch into any choiced mon (meaning that it is mostly run on revenge killers). It actually comes up very often due to how free slapping choice items onto Pokémon that get added boosts or speed control from their ™ is (See:
This Team that I used prior to the Trickeroo Ban in the status spam meta).
It's actually the reason that I've seen certain stall players try using things like disable Gardevoir in recent days. Choice items are that centralizing.
TL;DR
- Dancer choice mons get robbed of a turn if forced to dance prior to attacking (Intended mechanic).
- Skill Swap ™ grants free switch ins on choiced mons and does nothing else.
- Neutralizing Gas grants free switch OUTS to Weezing when its staring down a choiced mon with a ™.
- These aren't "broken" (as in unintended).
- These aren't "broken" (as in uncompetitive).
- These aren't "broken" (as in overcentralizing).
- These aren't "broken" (as in overpowered).
- There's no reason for a ban.
- Consider switching to life orb or any different item if you're afraid of this happening to you.