I've never done this task specifically, but I imagine the new google model (Gemini 2.5 Flash Image) is what you want. It has really good character consistency, so you should be able to paste a single sprite and ask it to generate the rest.

This is possible, but mostly for generating assets in the somewhat same style that you already have. Problem is that AI models are not good at tracking state of multiple entities on one image including 2.5 Flash Image.

If you actually want something consistent you should really generate images one by one and provide extensive description of what you expect to see on each frame

And if you want to make something like animation it's only really possible if you basically generate thousand of "garbage" images and then edit together what fits.