Having the weight gain stick around for all the animations would be a special hell tbh. The filesize would bloat dramatically and generating all the videos would also multiply the time it takes to create a single girl. I don't plan on making the weight gain stick around.
I have an idea forming in my mind to have the inbetween matches have a backdrop of you with stages of weight gain and your sentient fat with thought bubbles but that would come long after I've added a nice full roster of girls as opponents. I think 2-3 is far too little. So I'm prioritizing that work.