So a while ago I got the chance to have Lux's baby forms drawn and I went with the obvious answer, which is: YES!
Quite early on I had some basic ideas of what her prior forms would look like. I also had to decide if I wanted her Rena form to be a rookie or champion, since she's closer in power to a champion.
Ultimately tho I decided that no, the Rena form we're used to seeing is the Rookie, it's just a very strong rookie, which also fits very well because I still haven't finished what her first evolution looks like.
Anyways here's her baby 1 and 2 forms. I'm actually at the point in the novel where she's about to go to Baby 2 so I got this at a perfect time as I can now describe the forms the same way each time.
Her first lil ball form is/Baby 1, is called Ojomon. Early on she only had one eye but over time I grew to like this two eyed form better. I also liked the name so it stuck. She's surprisingly cocky in this form even tho she's just a tiny ball. But she was young and full of innocence and being as smart as she is she did grow to have a bit of an ego. Unfortunately she can't do much in this form. She can bounce around, quite high, and connect to things. Her attacks are very weak: She'll either jump on her enemy, or bounce up on them from below which is somewhat effective as she's quite heavy. She has one ace up her... uh... sleeve? Ear? Tail? It's that her visor can give off an intense and super bright flash of light. It's very convenient to blind unaware opponents and escape. Or tackle their weak spots which she's very good at finding by analyzing the target.
The next form is her Baby 2. It's called Visiomon She's a lot more agile now and can actually be quite dangerous as her head is made out of steel. So she's like a tiny, fast moving wrecking ball, that will headbutt your shins with no remorse and it will hurt a lot. It's not really all that dangerous but it'll hurt, and she can still use the bright flash of light to also blind opponents. So attack-wise not a lot changes but since she's faster now she can scheme a lot better. So her main way of offense is to brutally annoy an enemy by headbutting anything fragile and then running off, hoping they won't notice any traps she manages to make.

As she evolves, a bigger and bigger part of her brain/CPU unlocks as well, since the bigger frames have space to generate more power. Initially, both her baby forms were severely limited as to not overwhelm her. So Ojomon was pretty much a slightly glorified computer at first, and then unlocked it's full potential later. Same thing with Visiomon and her current Rena form(That I do have a name for but I'm saving it.). So technically she sorta evolves twice in each form, which I feel would explain the stronger Rookie form.

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