I am the only trainer to have won a standard tournament with Rosalina. My Rosalina is the only accomplished Rosalina in the scene to my knowledge.
Rosalina does not know how to operate Luma. The amiibo AI is only aware of Rosalina’s movements, and only sometimes understands Luma’s hitboxes. Rosalina will sometimes use her side special, Star Bits. That is not a reason to use Luma. Pretend Luma doesn’t exist.
In addition, Rosalina will spam neutral air if you allow her. Neutral air is useless. Avoid it.
Rosalina will operate mostly in the air, especially against heavy opponents. If she’s on the ground, it should be to either use a smash attack, or a dash attack. Otherwise, we’ll want her to be up in the air, using a forward air, up air or down air.
How to train Rosalina
First, as always, start her off at level 1. If you are going to apply any Spirits, apply them now.
Set up four 5-minute matches on Final Destination. In this match, you are only going to use one of a few moves. On the ground, you’ll use dash attack to get your opponent into the air, and follow it up with forward air until they die. If they’re at high percents and are on the ground, use forward smash or down smash.
If they’re up at the top blast zone, use up air and KO them. If they’re near the bottom blast zone, use down air and KO them. If they’re at the side blast zone, use forward air and KO them.
That’s everything I did to train a tournament-winning Rosalina.
Why it Works
Forward air is her biggest asset. It traps large opponents in, builds damage, and the set knockback is large enough to KO with. If used at the blastzone, the set knockback and knockback scaling together can net early kills. In addition, opponents have a hard time seeing her up air and down air hitboxes, so they don’t dodge them often. Opponents also can’t see Luma, so Luma’s hitboxes are typically what kills.
Thank you for reading! Good luck.