As seen here http://www.magnet-schultzamerica.com/electro-magnetic-products/magnetic-latches . They could be used to hold mechanisms in 18x18x18 position and then give bot Transformers power. We would like to use them for deployment of spring loaded slide boogie wheels from the underside of the bot.
It would be cool to have bi-stable solenoids like this, but not necessary. A lot of teams used rubber bands to hold in their intake roller arms for Gateway, which would release when the rollers turned during autonomous. This method could also be used for your extending wheels. The nice thing with VEX is that it’s easy to solve problems with rubber bands and zip ties, and you don’t need to buy new fancy parts to do every little thing on the robot.