One of the few good sprite series out there.
This series has a very well thought out storyline, using themes from Super Mario Bros and Sonic put together in the the style of Dragon Ball Z. However, its actually better than DBZ series because in the show more than half the episode is spent in characters thinking about their actions and not actually executing them. Your decision to use sprites was wise, making the majority of the episode action (well, this one had a flashback, but the action is good portion of it) and not so much wasting time talking, which you used only minimally, even provided the viewer to option to skip all that mooshy crap.
Also, this sprite movie is original in the action scene, which executes 3D movement (when mario kicks a koopa through the wall and the camera turns to view the back of it) and the fighting was creative every second, and not simple, punch, kick, and throw. The music was high tense, keeping the attention, and loud sound effects to keep interest and shock.
The characters were developed in a similar style to that of DBZ. Goku, who always does it right, like Sonic. The pussy one, (i forget his name) portrayed by Luigi, Piccolo portrayed as Shadow. And mario and yoshi are similar to their video game personas, but fit the storyline anyway. The koopa bros are a typical bad guy in the series who seem to give off the vibe of "these guys are easy to beat up" but are actually tough. Metal Sonic, obviously, the main antagonist like Frieza or Cell. The bald guy (forgot his name) to E Gadd, and princess, like herself.
Not to mention the opening and ending of the episode reminded me of the series.
The choice to not have voices but "ughs" or "urghs" or "Luigi!" instead is wise to have flow.
10+!