Emerald Imperium for someone who's only played the main games?

you don't need other hacks under your belt, knowing the main games is enough. just know it's built to be harder than vanilla. trainers have real teams with items and proper movesets, and it uses newer mechanics plus a lot of later-gen pokemon. if your usual style is overleveling one starter and clicking through, you'll hit a wall. plan your team a little and it's a great time.