Champion

Champion is the 41st level in Pokémon Tower Defense.

Description
As you enter the Champion's Room, you come face to face with a mind controled Ash Ketchum. Mewthree, using Ash as a channel, curses you for coming this far and challenges you to a one-on-one battle.However, after beating him, the mind control does not break. Then Joey comes into the room with Ash's Pikachu in his head. Mewthree gets enraged and appears before you and claims that he will take everybody with him in some sort of suicidal attack. Just in time Mew appears and tell him that, since he is made from Mew's cells, Mewthree is his son. Mewthree finally finds peace and swears to repay for all the damage he caused. Then Ash and Joey start a musical act of Pokérap, with all the sprites of the 150 Pokémon appearing in the scene (Mew was not included in the Pokérap).

Layout
Waves: 6

Spots: 1

Strategy
Well, I used all these at level 100: Venusaur - SolarBeam Gengar - Psychic Dewgong - Ice Beam Golem - Stone Edge Arcanine - Fire Blast Starmie - (Didn't use it in battle)

Imagine this is an actual battle - any Ghost can beat down Snorlax and Primeape, mainly with Psychic as it's super effective against Primeape.

Pidgeot was no big deal - Ice Beam, Thunder, Thunderbolt, anything like that can beat it with ease.

Squirtle and Bulbasaur have low stats and will fall down against any Pokémon that beats them by Type matchup.

Charizard is same as the two above, just with higher stats. If you're not level 100 or don't have a type matchup to beat it, in few Pokémon, you should be able to beat it easily.

An even simpler strategy

A Gengar can beat the whole level by itself. You will preferably want it level 100, and to know Psychic and Thunderbolt. For the Snorlax and Primeape, you will want to use Psychic, and Thunderbolt will easily take out everything else.

 Even more simplified strategy 

A level 100 Machamp with Cross Chop can take out all of the pokemon without getting to less than half health. Should something go wrong, you have six Max Potions.

 Other Pokémon that can single-handedly win this level  (when at level 100 or somewhat lower)
 * Alakazam (a lvl 66 one is already sufficient if you use a potion or two)
 * Mewtwo
 * Victini (don't use V-Create, though)

Trivia

 * When the level was first released, together with the Elite 4 level and Unknown Dungeon level, a bug would cause the screen to go black a few seconds into the level, essentially freezing the game.
 * The setup of this level is the closest PTD has come to a Pokémon battle like in the official Nintendo games.
 * The level is way easier than the previous level, the Elite 4 level, and most people thought that it would be really hard, but it isn't.. are you planning a new challenge level, Sam ?