I saw your question in the Shiny Thread about SRing for Sycamore's Bulbasaur, and yes, you can actually get it later on. When you battle him, you have to have a full party of 6 Pokemon, and then when you select Bulbasaur, you can decline to send a Pokemon back to the PC, and then you can leave and come back whenever to SR. It also makes SRing much faster, because you won't have to battle him each time. Hope I was helpful!