This guy is one of the strongest allies in the Aggression pool for sure. Yes, there are many candidates that deal higher amounts of single target damage, and some that go through a process to deal some kind of AoE. But Two-Gun Kid provides raw power, without the extra steps, without anything else but a single minion needed on the board. Dealing 2 against one target and 2 against another is amazing value, which can be taken even further with Boot Camp to essentially turn him into a Melee generator, or even more with Sidearm. The fact that he's an Avenger is also a huge plus - probably the most frequent trait to use with Team-Building Exercise. There is also Avengers Tower to discount him in an Avenger-heavy deck. Two-Gun Kid is one of the few allies in Aggression that makes it worth keeping a First Aid around for a consistently good damage source that doesn't rely on some random factor or rare niche scenarios.