Aliens have such great swarming potential with Snake Whistle, Crop Circles, Mysterious Triangle, etc.
Then, they get support from Offerings to the Snake Deity
They have their own built in backrow defeater in Gol'gar and Telepath.
Something like Normal Summon an Ammonite, special summon Dog from the hand and drop some counters; using Ammonite's effect, summon a Telepath, use the Telepath's effect to bomb some cards, then Synchro out into Gol'gar, drop some Big Bang Shots or something and sweep the S/T on the field.
Aliens have lots of field wiping and Special Summon possibilities.
With stuff like Shocktroopers and Overlords, it's easy to wear down your opponent's life points quickly too.