PTD: Pokemon Money
PTD's economy is run on three currencies: Pokedollars, Casino Coins and SnD Coins. The first, Pokedollars, are earned in stages. They are used for leveling up Pokemon, purchasing the evolution stones, and supporting skill learning from relearning or through HMs/TMs. These are relatively easy to earn and while it may seem that saving coins seems hard at the start, it is actually pretty easy. This gets even better once you get to chapter 3 route 5 - this stage is relatively easy to finish and once you have strong enough Pokemon for it, you can keep farming it for a pretty good profit. Just leave your Pokemon, set the stage on 4x speed and you will earn plenty with each run (and you get to level up a few Pokemon as well).
The casino coins are bought with Pokedollars through the daily gift and they can also be won from the game store. You can buy them as early as day one through the daily gift once every 24 hours. You cannot use the coins yet, and at 1000 (or 10,000) Pokedollars a day, it may seem a little costly. But if you plan on playing the game for the long run, it is actually worthwhile to start buying as many casino coins as you can early on. Once you get further through the game and earn your fourth gym badge, you will be able to access the Game Corner in the trading website. There, you can use your Casino Coins on the slot machines to increase them or spend the casino coins on a selection of Shiny Pokemon.
We highly recommend hitting the slots. You can only play 50 times per day, but the earnings are really big. Each try costs 5 casino coins, but you can easily earn 80, 150, 1000 or even 3000 coins. The chances of winning are actually pretty good so expect to earn back that initial 250 c-coins easily - not to mention making a pretty big profit out of it as well. Once you have bought all the available shiny Pokemon, you can try your luck with the random shadow type chance - it costs 300,000 casino coins, but if you have nothing else to spend it on, it becomes a pretty good investment.
Lastly, there are SnD coins which are purchased with real money or won through the game store. With SnD coins, you can purchase some extremely rare and exclusive Pokemons (such as the legendary beasts and some shiny versions of unique Pokemon). Getting SnD coins means having to spend a bit of cash. That said, Pokemon Tower Defense is an extremely well made game and any form of financial support from the players would be a great help to the developers (who actually work hard at providing updates, fixing bugs and are generally the ones we should all thank for delivering such an excellent game).
If you do not have the option of buying SnD coins, you may get lucky with the daily gift and actually win a few coins. The chance of this occurring is actually pretty low - the odds are naturally stacked heavily against you. But it does happen - there are plenty of players in the community who have already won 1, 5 and even 20 SnD coins through the daily gift chance. As we just said, it is advisable to start buying the daily gift as early as your first day. As you progress through the game and unlock the uncommon and rare daily gift options, you also increase the chances of earning those much coveted SnD coins.