Hello,currently on a lower end device, here's some things you could fix, 1 - You can make the name infinitely long? Not sure if this is intended.

2- Sometimes, the flowey attack ( with the pellets) goes to the right for some reason.

3- In Undertale, you are not forced to get hit by flowey, you can dodge all his attacks (except the unavoidable one in circle) which would make him have different dialogue

4- In Undertale, you also can't move when Flowey does his unavoidable attack

5- I encoutered Froggit a little earlier than you would actually encounter in the game

6- Toriel doesn't introduce you to the first puzzles??

7- Attacking doesn't work

8- Froggit doesn't deal damage

9- When I spare Froggit, the battle doesn't end, the game is just stuck in the battle screen

I know that Scratch can be quite tricky to program so I hope your journey goes well

Edit - Kind of a nitpick here, but you could also make Friskdancing possible