I loved my teams, I honestly could never actually make up my mind, which one was my favourite. I would say all of them, but if I had to choose one it'd probably be in Platinum, my Houndoom. I honestly loved it and after using Rapidash, I was really glad I caught this amazing guy <3. He's saved me out of many tight situations, whether it'd be my saviour in a gym battle, or even against a champion, I just loved it for different reasons. It was one of the only Pokemon I managed to get up to level 90, which is a record for me and it will always have a special place in my heart.
As for my Heartgold, I honestly can't decide either. Although I think I'm going to say Arcanine, when I first used it in my HG playthrough that started all of my passion and love towards the great canine <3. It had diverse moves, was adorable to tag along with, saved me out of many situations and I just really loved it. It might of not been as powerful as my Feraligatr or some of my other Pokemon, but something about it just instantly made it one of my favourites.