You didn't kill Gary's Raticate and here is why.
1. Gary wants strong Pokemon to be a very jerky rival, and a Route 1 Pokemon isn't cutting the list for strength
2. He only battled twice with it, showing little dedication
3. The first time it was level 15 as Rattatta, and then the next time it was level 16, and it doesn't evolve till level 20
4. The replacement Pokemon (Execute) is much stronger once evolved in Every. Single. Stat
5. The moveset wasn't that great and the level was low compared to some of his other team members, showing even less dedication
Caption this Meme
