Johto Gym leader have schedule when they hangout outside their gym so you can add their phone number for re battle purpose in HGSS.
This feature make some problem in pokemmo when Johto added because they not seen in their gym while people try do their Johto Gym re run. They fixed this tho
Everytime you beat any mon (wild or trainer battle) you will always get exp and ev. When you reach lvl 100 the exp just lost, but you still gain ev if you don't reach 255 total ev