http://samdangames.blogspot.com/2011/03/level-4-on-pokemon-tower-defense-update.html
I talked about this game before, but sense its not a big update I feel it deserves a mention/refresh.
This games online community just continues to grow do the continues weekly updates. Its enjoying to play a challenging flash game that actually takes some time to beat. Luckily time isn't an issue as you can save and port your profile onto and computer your using at the time. Recently they have added a trading system, as well as a pokedex, challenges/achievments that unlock you "shiny" characters, as well as the occasional online hunt for a code to a hidden shiny pokemon.
The normal tower defense mode is still the main element to the game (as seen above), however recently they have gotten creative and made modes and levels that depend on you getting by towers with your Pokemon as well. This forces you to use your "energy" wisely and makes learning defensive type moves worth it as now your Pokemon have to be balanced in order to progress.
Considering this games been updated and improved this much before he has gotten to the third gym this games potential is amazing, its already pretty fun I can't wait to see the end product.