This character design is very good. Mega Typhlosion's details look similar to Groudon. When I first look at the character, the reds and browns flow well, but the reds and cyans seem to clash, even though they are opposite of each other. They take a minute to adapt to. Once I became used to the color contrast, I thought higher of this image.
Mega Typhlosion's anatomy is good, but there are some drawbacks. For the black line in between the cyan and tan fur, it appears there is a gap as it reaches down the back of the leg. The rocks on the right leg do not appear natural. One of them has a hard, red line at the bottom of it. The back-left foot is out-of-shape. There is no heal. These fixes should improve the image's vision.
Finally, there is a harsh edge at the bottom-right of the illustration. For a transparent background, this is a deadly error! If a client saw this mistake in the professional graphic design business, I believe this would totally nail you hard in the face! When your character is in a transparent background, your shadow must be smoother and it cannot bleed outside of the art board's edges. You can fix this by increasing the picture's canvas size or decrease the character's size. Do not just think about the positive space. Think about the negative space--your character's surroundings, including his/her shadow's surroundings. How far apart are Mega Typhlosion and his surroundings, which especially involves the edge of the picture?