I have a valentini puffer in a 30g tank that was supposed to be FOWLR. after a bit, I started putting prunings from my main tank in there for holding until I traded them. Aside from curiously picking at them occasionally and knocking them over, she leaves them alone. Since I got LED lights for that tank for Christmas, I will be adding some additional corals. Nothing expensive or high calcium demand because she could develop a taste for something. Plus I don't want to have to start dosing this tank.
Corals my valentini has been fine with: frogspawn, leathers, mushrooms, montipora, birdsnest, rock flower anemone (not a coral!).
No clean up crew in that tank. Only other inhabitant is an orchid dottyback. Both fish are very mellow.
Kim