Well BC, let me explain how I want it to work, it comes out to be pretty balanced IMO.
Lets say Light has a power of 100 and the enemy has a power of 100. These stats can be split anywhere they want, but their skill TOTALS are the same. When the enemy 'transforms' or powers up, if their TOTAL stats go up, Light will 'match' this with the ability I'm calling "Void Link" or something, but wont match it perfectly, and will still be about 2% under the opponent. So if the opponent went to 1000, as long as Light is in combat with them, her power goes up to 980. The enemy still has a stat total of 20 points over her. It doesn't fully nullify the transformation, but it doesn't make it very good either unless it reallocates stat distribution like it should.
And its only on transformation abilities, stuff like charging for a big attack Light doesn't spike up to match since its a very temporary power spike, and lets face it, that wouldn't be fair. Same for temporary buffs like say, Arcane Power or something.
Meanwhile if Light was say, 80 to a baddies 100 and the baddie goes to 1000 from a transformation, Light goes to 780, keeping the 20% difference, plus her 2% penalty for scaling up. Still the same difference scalar wise.
Because lets face it, Super Sayan transformations mean nothing but to show how far a character has come in story development in a flashy way and DBZ abriged makes a good point that powerlevels are sorta pointless, and even Toryiama says the same thing. Its all about character and story development really. I mean, you don't see Edward from FMA going Super Sayan or anything, but he goes from a scrappy wimp to being able to kill neigh immortal beings just due to story progression and character development. So they aren't really needed. And your worry is that she'll make 'bosses' not very good or painful, but its only when they transform and shes still at the same gap she was before.
Of course unlike the enemy, Light CAN'T reallocate her skill points, so her speed/strength/ext is always the same percentages, while the enemy can possibly swap around theirs no problem, so instead of 30str 30spd maybe they have 40spd 20str or something.
And she'll learn it down the road, not right away, so it'll be a few bosses in before this happens anyway. :P
Meanwhile I just finished Undertale, and its a good game. Don't mind the graphics being SNES era and you'll have a good time. Plus Muffet is adorable.
my only complaints are that Light is basically a combination of an absorbing android and Buu, that just seems like too much. Also the purpose of transformations are that while they give a boost a person can burn through them quickly and it will be taxing on the body if they aren't trained properly. Super Saiyan 3 is incredibly powerful, but completely destroys the user's energy reserves after a short while. Light's answer to power gaining doesn't seem to fit the concept of how power gaining works in Dragon Ball. Dragon Ball was almost about training harder to achieve more power and pushing limits and breaking through them.
I'll be honest, Light seems like a Marvel/DC character put into the Dragon Ball setting.