i'm in your conscience
I don't think you need Baton Pass. You could get Smeargle to level 100 and have it know False Swipe, and just carry a lot of healing items. That's what I see most people doing. Everything else though (Mean Look and Ingrain) are fine. Baton Pass though, eh. I'd only want that as a last resort type of thing. I think Smeargle at a high enough level is capable of holding its own as a trapper.
edit: idk if you meant to ask this just for SS (since that's what you're playing as you stated), but next time you have a question for a specific game, please post it in its corresponding thread. I went ahead and merged it into this one for now, since it sort of applies to other games, but your post is really generalized towards HGSS, so yeah. Just keep that in mind next time, please. :)