>>42857089My favorite stuff from rom hacks and fan games is stuff like being able to improve my pokemon by changing IVs and abilities. It makes me feel like my team is getting stronger with my trainer instead of feeling like I have to grind breeding or chaining tall grass which is boring and isn't the same as using the bros I beat the story with.
A great thing about the battle frontier is that it adds variety to the gameplay. Like the battle pyramid was a maze, the battle castle and facility are kinda like rogue-likes, the battle subways had triple and rotation battles, multi battles with NPCs or another player starting in Emerald. With some originality in different ways to battle you can make your rom hack stand out.