Firstly, you need to change your starter pokemons attacks to:
Step 1 :
Click 'Trainer Battle' and enter the trainer number: 482301 Then start the battle!
Step 2 :
You should attack the ShinyBlissey's by following these simple instructions:
Just keep repeating steps 5 onwards.
This should defeat the Blissey and not touch your HP.
Keep doing this cheat through all 6 ShinyBlisseys and your Pokemon's level will get higher and you should gain more and more money!