Awesomenauts
It's a 3v3 2D platformer lane-pusher with an art style reminiscent of a saturday-morning cartoon. The upgrade system is very simple compared to other lane-pushers, and the games tend to go a lot quicker (15-25 minutes.) It's very intuitive to get into, but still has room for a lot of expression of skill.
Unfortunately Ronimo (the company who made it) went bankrupt in late August, so the matchmaking server went down in September; but recently Atari bought the rights to the IP, so it's possible it will come back soon.
They actually don't have last names; their full names are Mario and Luigi.