That's the thing though, I didn't equip any items with stated jump height increasing effects.
Here is the load out, for anyone who wants to try it (and I highly recommend you do):
The increased running speed effect is actually a multiplier of 1.3, so her Speed stat actually sits at +91.
The first hit bonus grants her ten seconds of invincibility if she lands the first hit in the match.
The power reduction might seem off putting, but it actually works well here - Rosalina is so fast in the air and on the ground, that it's really hard to get a hit on her, and Luma Warp can be acted out of really quickly. Luma is unaffected by the equipment, so he's still a KO machine (and Rosalina can still KO surprisingly well).
Her combo ability is also amazing with this loadout. Grabs can be comboed out of easily even at high percents.
Also, I equipped Launch Star Plus as Rosalina doesn't need the assistance of the regular versions horizontal option, since her air speed is so good.