Upgrading Skills

In Haypi Monster I've upgraded Nature Boost and the results aren't amazing. Only the SPD is improved but the damage boost wasn't increased.

I think it would be the same here also.
Thank you, now I can let that move out of my mind

It would provide some utility on a Faerivy with it's miserable SPD poor attack. It'll let you nail a foe for a mediocre hit while waiting for Malicious to do it bit. And with the SPD boost you will probably all you to be able to get Photosynthesises off before your opponent finishes you off.

That said Nature Boost is expensive, I use Paralysis Powder to SPD drop my opponent while giving the odd free turn for Malicious to do its damage.