Fanfiction Evolution Logic

So, I'm thinking of writing a battle scene where Bronze and BIGJAW fight alongside Hau and Gladion the first time they ever meet Guzma. However, they lose badly. Hau has a Dartrix so that's not going to do any good against a strong bug type. Gladion's null just isn't strong enough yet. And BIGJAW loses because of the whole reason this thread was even started.

The story is that BIGJAW had just evolved into Feraligtr back at the Aether paradise. So after some other plot, they make it to the third island and the battle starts. Now, my whole reasoning for why BIGJAW gets his scaley posterior handed to him is because that he just evolved and this new form is drastically different from his other forms. Croconaw was just a slightly bigger and bulkier version of Totodile. So, he wouldn't have as much of a hard time walking and battling. But Feraligtr is on a whole different level. His anatomy is much bigger as well as his size and overall way he walks.

One of Feraligtr's dex entries even states that Feraligtr has a hard time supporting its own weight. So my logic is that he'd have a hard time fighting after having little training in his new form since his trainer wasn't aware of this new form fanatic.

BIGJAW would have a hard time standing on two legs so he would be on all fours for most traveling. Then, whenever he throws a punch, he'd fall forward thanks to his new, heavy, muscled arms combined with the rest of his body weight. He'd also overshoot whenever he'd use waterfall, sending him flying into a wall. Next would be running. He'd stumble just to keep balance on two feet, leaving him open for attack.

Bronze would then note this after they lost and train with BIGJAW by pitting him agaisnt his dad's Tauros. Testing his agility by making him dodge his lasso. Riding on his back to help him focus on balance and strength. And even sparing with BIGJAW, himself.

This is just how I think this is how a drastic evolution would be handled. Any suggestions and critiques would be appreciated. But, if you agree then thanks, I guess.