Like Kyogre it has a 50% chance(or maybe you "cant" recruit it)
I believe if you look at red rescue team it is the same.
groudon
Groudon is located in Magma Cavern. He has a -10 chance of recruiting.
you cant
probably squirtle or mudkip, because of groudon.
try the groudon dungeon or joy tower
Its preatty hard to get groudon on red rescue team,so you should be the diamond rank or the lucario rank,you get a cool statue if u r.Just keep battleing him and u will eventilly get him.keep your head on,it takes a long time.
Groudon can be found in Magma Cavern. U can Recruite him later on in the game. Good Luck... Charizard LvL 100
magma caverns
There are a total of 26 floors.
Volcanic Pit is an area exclusive to Pokémon Mystery Dungeon: Red Rescue Team and Blue Rescue Team. It is a friend area that you get when Groudon has joined your party.
To recruit Groudon in Pokemon Mystery Dungeon Red Rescue Team, all you need to do is go to Magma Cavern , go to the final floor, (there are just under 30 floors) and battle Groudon. To increase recruitment rates, have your rescue team leader holding a friend bow, have a high rescue rank and level. **Make sure that the rescue team leader (you) hits the final hit on the Pokemon that you are trying to recruit, and m make sure that you have enough space on your rescue team for groudon to join.** You can only have up to 6 stars of space on your rescue team, so 2 starter Pokemon or one larger one, you can check its size under 'summary.' Egrentii