I wrote a program that simulates the exp gain for trainer's Pokemon in gen 5 and plugged yawnfag's Lucario into it against all the trainers in Route 16, Lostlorn Forest, Route 5, and Elesa's gym.
https://pastebin.com/b4kqJgxKThis is the output:
Lucario is currently level 34 with 33084 current total EXP
Level 34 Lucario gained 413 EXP
Level 34 Lucario gained 782 EXP
Level 34 Lucario gained 919 EXP
Level 34 Lucario gained 404 EXP
Level 34 Lucario gained 404 EXP
Level 34 Lucario gained 788 EXP
Lucario leveled up!
Level 35 Lucario gained 942 EXP
Level 35 Lucario gained 695 EXP
Level 35 Lucario gained 868 EXP
Level 35 Lucario gained 431 EXP
Level 35 Lucario gained 980 EXP
Lucario leveled up!
Level 36 Lucario gained 194 EXP
Level 36 Lucario gained 129 EXP
Level 36 Lucario gained 1003 EXP
Level 36 Lucario gained 327 EXP
Level 36 Lucario gained 817 EXP
Level 36 Lucario gained 409 EXP
Level 36 Lucario gained 323 EXP
Lucario leveled up!
Level 37 Lucario gained 312 EXP
Level 37 Lucario gained 908 EXP
Level 37 Lucario gained 649 EXP
Level 37 Lucario gained 306 EXP
Level 37 Lucario gained 664 EXP
Level 37 Lucario gained 475 EXP
Level 37 Lucario gained 844 EXP
Lucario leveled up!
Level 38 Lucario gained 817 EXP
Level 38 Lucario gained 377 EXP
Level 38 Lucario gained 377 EXP
Level 38 Lucario gained 460 EXP
Level 38 Lucario gained 1031 EXP
Level 38 Lucario gained 879 EXP
Level 38 Lucario gained 440 EXP
Lucario leveled up!
Level 39 Lucario gained 1333 EXP
tl;dr zero grinding took place, yawnfag is correct as per usual, sagefag is a gigantic faggot, and the exp curve in gen 5 doesn't nerf exp gains nearly as much as retards think it does