Charizard: My favourite of all starters, because it's a dragon. However, I didn't want to go all out European dragon/dinosaur or too lizard like for this guy, and so I tried to fuse some of those aspects together to get something a little less generic but with all the aspects of a dragon badass that it is.
Typhlosion: Mix of the Honey Badger and Wolverine. Typhlosion is a quadruped, but is easily bipedal. However, it's so often depicted as a biped I thought it would be refreshing to put it down on all fours (although this version can easily walk on two legs). The flames on it's back are superheated quills.
Blaziken: The hardest but the most fun to redesign. Blaziken looks way too humanoid and Digimon-like in the canon (cough Birdramon cross Agunimon anyone?) and I needed to stray from an anthro looking creature. Based on a Shamo Cockfighting Chicken, Secretary Bird and the Cochin Chicken for fluffy legs. Edited the leg anatomy too, from Plantigrade to Digitigrade, looks way more natural.
Infernape: Not an ape, it has a tail. So based it on Old World Monkeys such as Langurs and Macaques. In the wild they're naturally found with yellow swilrs on their bodies, but many trainers add traditional gold braces to protect them in martial arts. Looked cool that way.
Emboar: Tried making this guy bipedal with massive arms, looked stupid. So my version is on all fours. Based on a Wild Boar and the prehistoric Daedon (which was massive). Again, they're found with natural golden swirls on their fur, but usually have a metal belt attached, probably for fighting or tradition.
Blastoise: Heavy armoured terrapin/tortoise, with the face of a Snapping Turtle. The jets are based on the Mollusc Siphon(cephalopods mostly), and the muscle tissue can extend, harden and rotate so water pressure and accuracy is increased (in before dick joke). The thing is, these siphons are very vulnerable compared to the rest of Blastoise's armour, so many trainers incorporate metals plates for protection.