The enemy waves appear in a pattern: top left, bottom left, bottom right, top right. This repeats until the end of the level. If you can memorize the pattern, you can easily set up for the next wave before it appears. If you can't memorize it, keep scrolling around the screen at every moment (use the Pokéball to stop enemy movement if necessary) so you can quickly move your towers to the enemy Pokémon or change the screen size to 50% or 25%, this way you can keep track of the waves and Pokemon.
If you don't want to lose any candy, win the Achievement, and defeat all Celebi, bring: 2 Victini with Searing Shot to deal with all the Pokémon except Celebi; 2 Butterfree with Bug Buzz for Celebi; a Nidoking, Nidoqueen, or Arcanine with Helping Hand; and someone who learns Light Screen, like Pikachu, Clefable, or Mr. Mime.
- Fire Blast
- Bug Buzz (Recommended as Celebi has a quadruple weakness to Bug-type attacks)
- Silver Wind
- Aerial Ace
- Fury Cutter
- Searing Shot
This one was very tricky at first, but then I figured I didn't have to fight the Celebi. There are 10 candy and only 8 Celebi. If you only let them go away and save your Pokémon from dying to them, you'll be fine.
As for the other attacker on your Pokémon, abuse the allied Celebi's heal. It will take a Pokémon from fainting to full HP in around 15 seconds. So be aware of switching Pokémon when they are taking too much damage. At no point of the stage are all slots in danger to be attacked.
DO NOT use Missingno. They die with one or two attacks from any Pokémon.
Moon Snail's strategy
I have not yet completed this (Because I don't have level 60 pokemon) But I do think this strategy will work.
First, you will need level 60 on these pokemon:
- Any Fire type (I'd use Charizard)
- Any Flying type (NOT Missingno like the above strategy says, He's KO'd in 1-2 hits)
- Any Bug type (Like the first strategy said: Celebi's 4x weak to Bug.)
- A Ghost/dark type (For those Celebi)
- 2 others. probably tanks (Note: Do not use GRASS types or GROUND types.)
Hope this helped!