When I was picking my character's species, I was pretty stumped. There's many Pokémon I like and like you, many of the evolutions I liked were usually the last one. Of course, it's the one you will be stuck as, so the final form should be good - but due to how long it takes to get there, you have to make sure that you will find the other ones enjoyable too! You'll be stuck there a looooong time too, maybe never even reaching the final stage.
Like take Tyranitar, I really like it too, it was one of those Pokémon I got as a kid and I had no idea it even existed before I evolved a Larvitar. Larvitar is fine too, but Pupitar... Well, it's a bit strange. At least I would find playing as a cocoon without hands or anything to manipulate items with quite difficult! Probably the main reason why I didn't pick a Larvitar myself despite quite liking the evolutions, just because I felt like it would be that kind of awkward I didn't really want to deal with.
But of course, the most important thing for me was that the character I wanted to play looked right. I had Varda's personality idea pretty much set in stone when I started looking for a roleplaying site. Could he be a Tyranitar? Maybe. But in my eyes, he doesn't really feel like one. A fluffy bird suits him much better and Swablu/Altaria aren't even one of those favorite/most used Pokémon I got. It was a pretty strange choice, but the more I thought about it, the more right it felt.
Should you go in and play what species you like the most and develop a character based on that? It does work. But what if you decide on a personality/backstory first and then look at what Pokémon fits, even if it isn't one of your favorites? What do you want to play? Maybe you would find the idea of roleplaying a character without any way to really use items interesting, as that kind of quirks really can make a character and give us reasons why we enjoy roleplaying as them. I know I like the idea of having a little bird using its feet for anything that requires such dexterity. It's a pretty cute image but pretty strange to a human - even though there are humans who have no arms and do things with their feet instead!
Sometimes as a roleplayer, it feels like our characters go against what we first thought they would do. Sometimes what works better for them isn't what we wanted to do, but instead what they want to do. Experiment a little and you might come up with something you never would have normally. I know that has happened many times to me.
Subject: Need some help 
