Finding Ditto: After beating the league, i think 2 times, go to Fallabor and into the fossil maniac’s house and there will be a cave at the back and you will find ditto around 30-50 lvl dittos
Safari Zone: after beating the league a new area of the safari zone will be opened will new pokemon, to get all of them, you need mach bike AND acro bike
smeargle: go to the waterfall @ the battle frontier near where u found smeargle (water it with the wailmer pail) and surf left and there will be a cave, go in and walk around and there will be lvl 40-50 smeargles.
Regis:
here are the steps you will need: pokemon with surf, dive, dig, flash & rocksmash
1) go to pacifilodge and surf to where the currents are. STAY SOUTH.. keep surfing below and eventually you will get to a small dark patch, dive there and swin south and read the code on the rock then surface up. walk to the end of the sealed chamber and read the code then use dig, a door will open. walk to the end and read the code, the ground will start shaking and it’ll say a door opened far away.
Registeel: Go to the big rock on route 120 (where a trainer said he thinks it leads to ancient ruins but there’s no entrance) now there will a hole. walk in go to the exact middle of the room and use flash. a door will open, go in and there will be registeel.
Regice: Surf down to route 105 and there will be a rock will a door, go in. read the middle code, then walk around the perimetre of the cave then read the code again, the door should open, go inside and there’ll be regice.
(Lastly…) Regirock: Go to the desert on route 111 and go down the most southerst point and a rock will have a door. go in and read the middle code, then press LEFT TWICE then DOWN TWICE then use rocksmash and a door will open and inside will be regirock.
TIP: save infront of each regi (they wont move until u talk to it) before attacking just incase u kill it, u will only see it once. and dont use master balls, get lots of pokeballs and chuck it at it for a long time, then after a while, use a timer ball or ultra ball, save the master ball.