Ok I will start off by saying they are both good stallers ,BUT one in my
opinion  is superior to the other  lets start off with the stats

Name:         Chansey 
Type:         Basic Pokemon
Card #:       card 3 of 102 
Rarity:       Rare - Holo
Color:        Colorless 
HP:           120 HP
Weakness:     F
Resistance:   P -30
Retreat:      1
Species:      Egg
Level:        55
Pokemon #:    113
Attack:       [2]  Scrunch  ()
              Flip coin.  If heads, prevent all damage done to Chansey during
              your opponent's next turn.  (Any other effects of attacks still
              happen.)
Attack:       [4]  Double-edge  (80) 
              Chansey does 80 damage to itself

Name:        Kangaskhan
Type:        Basic Pokemon
Card #:      card 21 of 64
Rarity:      Rare
Color:       Colorless
HP:          90 HP
Weakness:    F      
Resistance:  P -30  
Retreat:     3
Pokemon #:   115
Species:     Parent
Level:       40
Attack:      [1]  Fetch
             Draw a card.
Attack:      [4]  Comet Punch  (20x)
             Flip 4 coins.  This attack does 20 damage times the number
             of heads.

Here are the categories

Attacks This is probably the hardest category  kangaskahn lets u get a card
but chansey  has a 50\50 of preventing damage and we all know that their
other attacks sux snorlax dung  TIE 1-1

HP Chansey 120 Kahn 90 obvious Chansey 2-1

Retreat Kahn 3 Chansey 1 also obvious Chansey 3-1
 
Rarity Kahn rare Chansey holo Kahn 3-2

Chansey wins I used to love kahn  but after seeing him beat down becuz of his
retreat so i dropped his but and got ahold of a chansey the only reason to
use kahn is until u get a chansey  if u want to argue e mail me at
ace00098@aol.com