I think it's obvious already, but my favourite Pokémon is Heliolisk.
I think it's both cute and cool. Plus it genuinely surprised me how good it was in battle. It's not the strongest, but it can punch hard and it's pretty fast. It can learn Surf, which in-game is great for me since I don't use a lot of water-types (and Surf is needed in most games to be able to progress the main story), and in competitive it's also great since it gives it a lot of coverage.
I don't want to just post this chart without elaborating because it feels like cheating, but fuck me if I'm gonna be able to decide on a favorite mon in the next 20 years...
Haxorus and Sandslash have consistently gotten the closest to #1, but 1) I can't decide between the two and 2) the entire Deino line has been giving them both a run for their money, as has Archeops (which I couldn't include due to type overlap) and- for some fucking reason- Espathra.
Might as well repost the magnum-opus of my autism about this series while I'm at it. Gotta farm those puzzle pieces.
complete with spreadsheet analysis of where my favorites lie in terms of generation
Honestly I should probably be crucified for wasting so much time on this series but I love it so much man. You could probably ask me about why I like literally any design from the "love" tier up and I could write paragraphs praising and explaining why.