a building that catches pokemon for you, you pay a lot of money for a level one unevolved pokemon that you already caught (maybe seen for a outrageous price, minus legendaries)
a sewer that you must travel through which will have the event pokemon totodile. you can have ratata, sandile grimer koffing, trubbish and there evolutions.... when I was a child I heard rumors of people throwing aligators down the sewer....
a double battle with eevee and it forms person a has eevee, flareon espeon and leafeon, while trainer b has jolteon, vaporeon, umbreon, and glaceon, if we introduce sylveon (the fairyone) add it to person a, and add a eevee towards trainer b.