Hey, this all reminds me of a game called Cybernator (Super Nintendo). It was nice. I think there was a sequel too (Also on Super Nintendo), or at lest something very similar, where there was a lot of different mechs to choose from. In both games the mechs had shields they could use to shield off enemy fire. Both were awesome games.

The later one was really awesome, with its multiple playable mechs. I remember this one that was a ball that could alternate the shape of it's shell for different purposes, like holding a plate of it's armor up as a shield, and unrolling into a tripod to fire. Anyways if this game is going to be anything like those games, it is going to be sweeeeeet. ... I hope the mechs can be exited. Leaving one mech and taking a different one is a nice touch. It is funny to chase after a little guy and try to stop him before he finds a new mech. It was a blast in 2 player battle mode.

I did some reserch, and I think the game was called Metal Warriors.

http://www.fantasyanime.com/museum/metal_warriors.htm .