First let me tell you something before you start. For this guide you will have to spend some money on supplies to get things done until you're ready for DT Grind or Farm.
Now let me tell you what you need to bring for training.
-Vitamin you need this for longer training. If you want to buy some food, then help yourself out
-HP Disk be sure to bring some, in case you don't want to spend on food
-AT or DE Plate (2 of each). AT for fast farming while DE help with living longer when fight 5+ above you
-Low lvl Digimon (Any kind will do)
Now let us start, from lvl 1 just do like many other tell you to do. Train till lvl 12 and move to Western Village at the Digital World. Next train there for some Mercenary Eggs for sell, after you have enough you should sell them in the map for 10 to 15M each (Some people would buy it)
Continue to the next map once you reach lvl 14, then train at Leomon or go to Eastern Outskirt for Dobermon, Agumon, Patamon and Deputymon eggs. They also bring some M if someone would buy them in bulk
At lvl 18 or 20 go to the next map and train at Sabirdramon (AKA Saberdramon) each cracked eggs they drop refund for 100B while the other only give 25B. Keep doing the same as the last map, but if you have the egg you want to hatch then keep them if you like.
At lvl 24 or 25 go to Wind Valley. Find the Digimon you like to farm and do the same like other place of your lvl, many of the digimon here give 25B for each cracked egg
At lvl 28 to 29 go find Cerberumon or Gatomon, their Mercenary and Cracked give good M. Merc Eggs give 15 to 20M (Some charge for higher) and cracked refund for 100B. Plus they are easy to kill
Move to the next map if you want Biyomon, Elecmon, Renamon, Agumon and Hagurumon (Mechanorimon line).
For Oil Refinery Area you can farm there if you like, but I would fight Veedramon for cracked (150B for egg) and some Veedramon eggs for Chip for sell
Once your Tamer lvl is 25 and your Digimon lvl is 42 or 43 you can train at Western village west. You can train at Pumkimon for Bakemon egg, Okuwamon for Kunemon egg and HellMetalGreymon for Agumon egg
Then move to DT (Dark Tower) once you reach lvl 45 or 46, early for None Rookie Digimon.
In DT you have to start with DarkWormmon all the Digimon in the Dark Tower Area give 250B for cracked egg while the mega form give 150B
For none Rookie digimon such as Kiwimon, Dobermon, Starmon, Deputymon, ect....... can train here at early lvl of 36 even better with AT plates
Now while you at DT you should train to lvl 60+ here, and while you're here you should stack up your cracked eggs during each run here. Throw away Attribute (If you already have them or a better), keep the data for chips which people buy them at Dat and through Chat
If you have a tamer 50-55 making money is quite easy
For lvl50 tamer there is now B2 remember the alluring icedevimon quest now this is the reason u should do it the digimon there is the same level as gizu but give more exp.The cracked eggs give the 2nd most amount of bits in the game plus the daily quest gives 100M a day. Farming monodramon eggs and sell for 20M ea each day will make you rich (did for me)
For lvl 55 tamer just skootch on down to maze entrance which is all the way to the end of DT talk to starmon of passion.Now this is the place where questing does matter its best to do them bcause they give u new maps.fight anything suitable to your digimon type and sell what you dont need. one stack of cracked eggs is about 50M idk i havnt played in a while
This is what you should do here:...........
Keep on training here for Money, fight even the blue just 7 lvl below you should do it
Move to DarkSkullmeramon if you have Good AT plates on your Digimon, my Elecmon kill them like crazy here (Data vs Data) and the result a lot of money and eggs plus fast lvl up
Don't rush for DarkVeemon, because they always full unless you want to lvl that all and the Digimon outside DT, they good lvling but worse on cracked