>>23436160Grind for coins on stage 37, Meowth.
Take one strong fighting type and 3 weak non-fighting types.
You can usually get four coins lined up which gets you 330 coins at the end, sometimes you can get five coins lined up for 530 coins.
So 5 hearts x 330 coins = 1650 coins
Do this a few times and save up for items.
Don't buy experience x1.5 or Moves + 5, they won't help you catch it. You might not want Complexity -1, simply because it's so expensive, or Mega Start because it's a 30 move stage, and it's not that big an advantage.
Make sure to get Attack Power Up and Disruption Delay, though. Make sure you have at 2500 coins left for a great ball.
Beat the stage, and see if you catch it. If not, toss a great ball, but if that doesn't catch it, exit the game with the home button the second it pops back out and close it without going back in. If you do that, it won't charge you for the great ball, and you save 2500 coins.
Wash, rinse and repeat until it's yours. There is never any need to spend real money on this game.