What routines? Sprites are hardware limited to 64x64.
You would need to stitch together 4 sprites in a 2x2 grid to create the illusion of an 80x80 sprite. Doing so on a static, unanimated sprite wouldn't be a problem regarding implementation.
The real problem is VRAM and screen space. Consider you have 1024 tiles of VRAM to hold all your images (0x7FFF bytes).
Code:
Tiles Item
256 Player Pokemon
256 Opponent Pokemon
8 Player Hp Bar
8 Opponent Hp Bar
128 Player Hp Box
128 Opponent Hp Box
32 Icons
64 Basic 64x64 attack
64 Attack impact
Total = 944 of 1024 tiles
As you can see, you're not really left with much to work with. Most moves are going to encompass more than a simple impact + attack animation. For example:
Overall, from an aesthetic and space POV, expanding to pseudo 80x80 sprites is not viable. If you wanted to do something like this, you should a) give up on double battles b) attempt to work around the limitations by loading sprites only when they are displayed and pivot the "camera" into showing perspectives with 1 battler at a time, as seen here: