A couple years ago, I was playing Platinum, and Gligar was a big part of my team. With a 430 base stat, she is one of the strongest unevolved pokemon that evolve later on. I didnt know how to evolve her, so I didnt. Recently, I traded her to Soul Silver, and she lagge behind while battling my friends, so I boxed her. I want to evolve her, but I am just so attached, and she is so adorable. Gliscor only has a 510 base stat, which is not a whole lot higher than Gligar. She is currently level 68. Should I evolve her?
Gliscor does have alot more use especially in wifi/competitive battling. The base stat increase may not seem so much but if you think about it, every base stat point increase is actually "2" points in real max stats, so even though gliscor is only 80 base stat points higher than gligar, it will actually have 160 stat points higher than gligar.
I understand how you feel about being attached to it, but even if you evolve it it's still the same pokemon, it'll still have the same nickname (if you named it), the same nature, and the same ID number. So remember that even if you evolve it it's still the same gligar you had way back then, it just grew up :)