Interesting RP thoughts.
I know you said you wanted to keep it strictly TFP (which is cool!), but if you want side characters before season 2, maybe allow fans’ TFP versions of TF characters from other TF incranations (G1, Armada, Animated, Beast Wars) to join? Though that might defeat the point. You may have to wait for season 2 if you want canonical side characters, I foresee season 2 increasing the cast. Though there is this: I don’t really buy it, but apparently War for/Fall of Cybertron is supposed to be in continuity with TFP, and they have more characters, even side characters. I don’t really buy them being in exact super continuity not because the games aren’t good…but because they don’t seem super exactly in continuity with each other. Designs are different, most voices are different, etc.—TFP and the games don’t seem to add up exactly, and I do want to see TFP-the-show alone basically make up its own continuity/story, though side comics in its aesthetic/style like the prequel comic with Cliffjumper, Arcee, Starscream and Breakdown are pretty cool.
…Sorry for the side rant. XD