This looks amazing, I love the artwork especially the grass type, feels like it could do some serious photosynthesis with that tail to give it energy! I think its an Oak leaf for the flame.. really cool. I would call it Synthe-sisnu or sisnu for short.
For the others I would call..

Normal - Kai-Nu
Grass - Synthe-Sisnu / Sisnu
Water - Nudew
Ground - Magma nuke
Ice - Isa-kai
Fire - Kai cindu

Or if I was being more playful...

Normal - Nunu
Grass - Oakatree
Water - Ria Krait
Ground - Pebbledash
Ice - spiketail, or Frow-yo
Fire - cinder wing

This was really fun, I hope the game development goes well.