Q. If EX-Sandstorm Pichu's "Baby Evolution" power is turned off by Muk's "Toxic Gas" power, does that mean that it cannot evolve into Pikachu?
A. Pichu's Baby Evolution is the only way it evolves to Pikachu. If that is turned off, Pichu can't evolve. (Sep 11, 2003 PUI Rules Team Meeting)