Thunder wave always hits, and it always paralyzes. Were you possibly thinking of thunderbolt, in which case the Ferroseed dosn't learn it.
Sorry, I guess I said that sentence with bad grammar. What I meant to say was that when you are paralyzed, then you won't move as often. You know when it says: Your pokemon is paralyzed! It cannot move! I think that will happen more often now. I'm pretty much done with talking about Ferroseed for now. Also, Skwog, when you switch in your murkrow, it can get poisoned, or paralyzed by Ferroseed. And I know what you're thinking. Prankster. But what if you can't move eh? Either that or you get poisoned by toxic, which then stalling aint so fun to do. Now with that out of the way, I will only post stuff about Ferroseed if I need to defend myself from your critisizms.