If the tall grass is in the first town, you should either change it, or give the pokemon BEFORE you leave the building you start in.
Anyway, I usually like hacks where you're part of the evil team, I don't love them because they don't seem to follow what the team seems like they do in the official games, but you could change that.
for the badges you could get them for pulling off jobs, like helping steal the sub, defeating the trainer that you play as in r/s/e, helping catch groudon after it escapes, etc.
You could have an event where you help find some groudon dna, like in the jirachi movie, deliver it to someone, on team magma or some random sucker, that will bring it back and well thats all I got for that
You could have events where you fight team aqua, and have to stop them from finding and capturing kyogre.