Gligar
HP: 65
Attack: 75
Defense: 105(157 with eviolite)
Sp. Attack: 35
Sp. Defense: 65(97 with evolite)
Speed: 85
Gliscor
HP: 75
Attack: 95
Defense: 125
Sp. Attack: 45
Sp. Defense: 75
Speed: 95
~Gliscor~
It pretty much depends on your moveset. A Gliscor running Toxic Heal and Toxic Orb makes up partially for its medium defense. However, one could make up partially running Eviolite Gligar with Earthquake/Aerial Ace/Steel Wing. Gliscor's stats are overall better and more suited for competitive battling, especially with Toxic Heal.