Lum / Rest is good, but grass has too many weaknesses that id only do it on a BP team that can pass +4 to both defences. Harvest is a trick room blessing however, and better suited for doubles so you wont need to switch for support. Not sure id either can learn fling, but Lum / Fling would be hilarious for doubles staus healing.
Speaking of Lum... doubles + Flatter.
EDIT: just lookes into it, the natural Harvesters can't but some skill swapers could i guess lol