Solarbeam
Earthquake
Eruption
Thunderbolt (thinking of changing it to Dragon Claw)
Its pretty useless to have Thunderbolt. My Groudon has a very high attack. It seems a waste not to give him atleast one attack move. Any suggestions?
However, some people really dislike AP (for some reason, I love it), so replace that with Rest if you are one of those. BTW, if you plan on using Groudon in tournaments, he is usually banned.