I've got one you guys may like! The actor who should play him is the guy who plays Blair.
Villain: Pokey Minch
From: Mother 2 & Mother 3
Abilities: The ability to influence any villain into making him powerful in some way by throwing cash at them (Either literally or figuratively). The ability to make Ness get ticked off and completely destroy his composure. The ability to use his family wealth to buy the best in war technology any time he so desires and use it against the heroes.
Costume: A simple white T-shirt and suspender shorts with only one being strapped. with knee high socks and tennis shoes would do. Or if you want him to look like a spoiled rotten rich guy, give him a suit that is unkempt and probably doesn't fit very well, being the fat slob he is.
Reason: Because he's a really awesome villain, Ness needs a rival to keep him on his toes, and lots of fun could be had.
How he enters: Pokey will be entering the show from between the events of Mother 2 & 3. Pokey entered a time travel rift at the end of Earthbound in his spider bot machine (which I'm sure could not be recreated for the show). You guys could show him watching Ness from afar, with a mischievous look on his face, to bring him into the show. His appearance shocks the daylights out of Ness and gets him all ticked off and ready to go down swinging if it weren't for his confused friends to hold him back and get an explanation as to who this guy is.
What he would do for the show: Pokey Minch would basically be the same thing to Ness as Gary is to Ash, except more like a spoiled bully who brags about his wealth and how awesome he is compared to Ness, saying things like "Haha! My parents got me video games and bought me the latest and greatest toys and you're still stuck with a yo-yo and a baseball bat!". Also, at times he'll appear as heavy eater, holding bags of chips or ice cream, food all over his face and shirt, and just annoy the heck out of Ness. He'll also have a penchant for power and anything that can make him more awesome. He'd do well acting as a bully to everyone. He can even have a butler come deliver him food in even the most inappropriate times. For instance, let's say Mario & Luigi and the gang are fighting a final boss or something. He'll be standing his ground, but get hit by a blast. On the ground he'll pull out his phone and ask his personal butler to bring him a pizza and just stop worrying about fighting to eat. Or even better: if he sides with the final villain and tries to help the villain in his goals by following false promises of wealth, power, and a lifetime supply of cracker jacks, he could seem more genuine.
The time machine he used to end up where the Stupid Mario Brothers are, was given to him by his parents (I can imagine a flashback scene where Pokey is standing in front of two figures who's faces you don't see, asking for a time machine, and his parents saying "Sure, whatever you say".) Being in another time, it may need to be explained (or not) how he already has a butler. Either the butler could be a time traveling butler because his parents do that for the butler too, or emphasis could be made on the extent of Pokey's ability to influence even the most hardened of villains, much less a simple butler. A good comedic way of getting him to influence people, is by throwing wads of cash at them (Either printed fake cash, or Monopoly money)
So that's my addition to this series! I hope it gets picked, but if not, I hope it at least gets noticed =}