UA's won't work in Duel Links, they are an archetype designed to swap eachother out from offence to defence after the Battle Phase during Main Phase 2, whci Duel Links does not have.
I've played with them and against them, they quite clearly are working very well on Duel Links and going strong against the current meta. The only difference is you cant switch them to defence Main Phase 2.
They are very aggressive in DL, which makes them viable. Their main setback is consistency...they remind me of Original BBQ Hazy Flame: Strong strategy, decent engine, inconsistent fuel *Tribute fodder*.
Except U.A. actually works better in DL than in real life lmao
Especially in DL's current format instead of the real life format (U.A. in real life first showed up during the start of Arc-V era, and took almost two years to get all their cards)