Since the new GUI for Essentials is based on HG/SS, I would recommend seeing about using the attack graphics from that.
The attack sounds aren't going to be hard to necessarily GET, there will just be a lot of them. My immediate idea would be to do it manually if we can't find anything already ripped.
1: Replace the game's battle music with a short, unlooped MIDI or a completely blank one. It's already possible to replace the music tracks in DS games.
2: Use a hacking tool to edit the first trainer's Pokemon in the game to know whichever attack we need SFX for.
3: Save before battle.
4:Record the sound, and recompile the nds with a new attack.
If you're able to distinguish between hundreds of unnamed sound files that don't include the 8-bit instruments, you can also try using VGMTrans.