Want Thunder TM.
To increase your chances of getting triple 7s. 1. Get a 7 in the first row. 2. Press and hold A for the second row. If a 7 does not originally show up, the machine sometimes rolls it to a 7. 3. For the third row, do the same as you did for the second row. The machine either spins itself to a 7, or Golem comes down and rolls it over to a 7, a Chansey could come out and throw eggs at the row until it hits a 7, or nothing happens at all and you lose. Side note: For the final row, the machine can do any of the possible "winning actions" (e.g. Golem rolling down, machine spinning itself) and still end up losing. Although I'm pretty sure if the Chansey one shows up, you will always win (not sure, would need confirmation).
I hope I helped, if not comment on this answer.
Source: https://gamefaqs.gamespot.com/boards/446340-pokemon-silver-version/44948161
