No, I don't think I have. I looked it up, and it's Barboach and Shroomish in R/S, btw. But Seedot in Shroomish in Emerald. I've never bothered with this because I never care to do it. But, now that I see you can get an Elixir by doing it, I might attempt it.
That's one of the few things in Emerald version that I never bothered to accomplish since it seemed like a lot of work for little payoff. I don't think I tried getting the Elixir prize in Ruby and Sapphire, either.