Talk to Chuck's wife in front of Chuck's gym or just use the action replay. To get Chuck's phone number by talking to his wife battle (you don't have to beat) Red. This goes in Heartgold and Soulsilver.4
Chat with our AI personalities
on thurs afternoons go to viridian forset and look for him
You need to get their Phone Numbers, by taking a picture with them at certain times of the week, and time zone. there is also a place where they will go after you get said phone number reference youtube for dates/times for the rematchs.
All of them have phone numbers, but there are certain ways to get them. I would try looking up "how to get all gym leader's phone numbers in heartgold" on google
its IPGE2D5118CA (soul silver) IPKE4DFFBF91 (heart gold)
Geodude evolves after level 35 in heart gold