You can find the Galactic Grunts at the top of Mt. Coronet. You will then fight 2 of the galactic commanders. You will fight them with Barry. Then, you enter the distortion world.
You can receive Riolu as an Egg from Riley in Iron Island after you helped him fight the Galactic Grunts at the end of the cave.
Fight some of the grunts there and 2 of the guys there will tell u the passwords
you go to the place where you saw two galactic grunts
you need to find the plasma grunts in the cold storage in the far left corner to fight clay
go to jubilife and go up to floaroma city and defeat team galactic
go to floraroma meadow and fight the 2 galatic grunts there they will leave when you beat both and you will get the key
get your strongest pokemon and fight the grunts find the grunt with the elevator key and then giovanni has a rhyhorn a kangaskhan and a rhydon
Go to the museum in Slateport. Talk to the grunts, one of them will give you a TM. Then go upstairs and talk to Capt. Stern. Two grunts will come. Fight them. Then Archie/Maxie will come and make bold claims. Your path will be cleared.
go into mt coronet from hearthome city then keep going through the cave (its annoying) after you fight many galactic grunts you finally get there
After you defeat all the Grunts and get the Magma Emblem, just go below Lavaridge town, then descend the ledges at the east, take the Trolley and then go below in the area where you fight all the trainers and campers.At a certain place, your Magma Emblem will react and a new cave will open up.Go in the cave all the way till you see Maxie and Groudon.You fight him and Groudon will dissapear.
you go to spear pillar and you will fight to grunts and mars and Jupiter with your rival. Then Cyrus will open a portal to distortion world and at the end you will find giartina.