This is really strange to me. Why not just run enough speed to outspeed uninvested Aegislash (lets you outspeed Jellicent too), and use Sucker Punch to bypass King's Shield?
It should be noted, as I'm sure has been mentioned in this thread before, that Sucker Punching when Aegislash uses King's Shield
will result in the attack drop on Showdown. I doubt it's supposed to work that way, however.
That being said, I've been running 4 attack Mawile (Play Rough, Iron Head, Sucker Punch, and Ice Punch), and it has been an absolute hammer. For me, Mawile has been most effective when paired with a
Gliscor. Because Gliscor is neutral to Dragon moves, most offensive dragons rely on the sheer power of Outrage to push through him. Gliscor can easily tank the Outrage and
switch or
U-turn (I keep going back and forth between U-turn and Defog on Gliscor) providing an opportunity for Mawile to come in uncontested. From there, the ridiculous strength of Huge Power generally lets me make a massive dent on anything that isn't Forretress (or Ferrothorn I presume, but I have, surprisingly, yet to encounter one).
As an added bonus, Mawile and Gliscor cover each other weakness very well.
Beyond that, I've been running
Scoliopede for the baton-passing synergy that has been previously noted. It's also worth mentioning that either Gliscor or Scoliopede along with Mawile probably warrants a
fire resist or two within your team as it is a bit of a common weakness. I'm running
Gyarados for more intimidate nonsense, as well as decent type/coverage synergy with Gliscor and Mawile.
The biggest thing I've noticed is that Mawile has completely changed the way the team operates. I began with Mawile and a dedicated "defensive core" (although it was really more bulky offense) as is standard, but Mawile reduced the team's reliance on this core by being able to threaten a kill almost every time it came in after one of my pokes dropped. That's poor wording, but I hope the concept makes sense. Almost every time my opponent KOs one of my pokes, Mawile can turn it into a near one-for-one situation by coming in for free and putting a huge dent in anything, even those who resist Fairy/Steel STAB. It's gotten to the point where I've disassembled the defensive core of my team, save for Gliscor and an offensive Latias, because it's hardly needed.
So overall, Mawile is awesome. Its fun to build a team around, and it creates a relatively unique dynamic that is a refreshing change from the last gen of OU to say the least.