Heck, what wouldn't she do?
For starters, she could use her sports outfit, and use the spin-offs as her arsenal.
-Specials-
N Special could be her Crystal Smash, and I guess it would work like DK's down B, but hers would be smaller, and it would need some time to cool off to be used gain (around 3 - 6 seconds maybe), but would have good knockback (If sweetspoted, it could have Zelda's side air sweetspot kind of knockback) and the player could charge it for more power .
Down B is her counter move
Side B is her throwing something. ( Super ball would have the most knockback , Dice block from Mario Party would have more launching power and a tennis ball would be the fastest projectile)
Up B Is... uh... I completely forgot what it's called, but it's her special from that one tennis game. She launches diagonally upwards, a small trail of quick disappearing flowers behind her feet. It would deal standard damage if an opponent touches the Flowers beneath her feet.
-Air-
Her N air would be her shaking her pompoms up and down from Mario Sports Mix
Side air could be a slow elbow attack, having meteor smash effect at start and/or end of it.
Back air would be kick behind her
Down air would be a Volleyball spike - slow-ish move, great for meteor smashing.
Smash attacks-
Side Smash - Daisy would be winding up a punch, sort of like Little Mac's, then hits the opponent with good knockback and power.
Down Smash - She charges a punch, then when released, se will hit the ground and a crystal will pop out where her hand is, it has launching power and fairly powerful strength, but It will only hit in front of her.
Up Smash - she delivers a strong kick upwards with one foot.
Final Smash - Mega Strike or maybe something else involving the stems of a plant with thorns. (?)