I once traded a lvl 58 Arcanine to a friend when I was 15. He needed help defeating the Elite Four in Sinnoh.
Well.. time progressed, and things happened. We grew apart. Far apart. Literally. And so our friendship (or lack thereof--nvm, rambling) died.
Growlithe is a pokemon that resonates with me because of its moveset. It is a loyal and dedicated pokemon. It gains power from protecting and avenging its allies. TO me, trading that Arcanine was--not then, but now--a symbol of my loyalty to that friend. Although we are no longer even acknowledging each other's existences, Arcanine reminds me of the good times, not the bad. I used to undermine the potential of Arcanine, although it is pretty strong. Now, If I ever decide to catch one, I raise it with much much more care and attention to detail than I first did whenever I play a game where I need one. And always, I am reminded of that traded Arcanine.