What would make things easiest at this point, Darkken, would probably be to still make the Mech Warrior sprite the same size (as in "number of tiles") as the Krawlie sprite, and the same number of frames for each animation that Krawlie has. There is no hard-and-fast limit -- it's perfectly possible to have a Mech Warrior with a gazillion animation frames -- it's just that if the number of frames Krawlie has is less than the number of frames Mech Warrior has, the CE team will have to make room for Mech Warrior's sprite assembly and animation data.
In other words, let's say Krawlie's animation set consists of three frames for walking and six frames for his "grab-an-enemy-and-pound-them-around" attack. That means it would be easiest if Mech Warrior had three frames for walking and some attack that uses six frames.
Again, I'm not that familiar with how much free space the CE team has in their latest build for sprite data, so I'm not sure what their maximum limitations are.