Rare Replay
200 Achievements
4,000
200-300h
A Particular Set of Skills
Battletoads Arcade: Over time, defeat 1000 enemies with standard attacks.
15
3.38%
How to unlock the A Particular Set of Skills achievement in Rare Replay - Definitive Guide
The last level has you in a space shooter style gameplay and all of the missles, orbs, fireballs, etc are considered enemies. My final count for that level alone was 800 and you should already have several hundred from the earlier levels.
As mentioned by Whiskey7, co-op kills will group together for achievement progress.
This achievement requires to defeat a cumulative total of 1,000 enemies across all playthroughs of the game. You'll likely reach about 600-700 from a single playthrough (the majority of which will come from the final stage), so if you're completing three full playthroughs this should come naturally during the course of your second playthrough.
Alternatively, if you're using multiple controllers to avoid needing to complete several full playthroughs, make a manual save just before the boss of the final stage. This boss encounter sees the boss attacking with an unending number of projectiles, each of which count towards this total. Replaying this encounter once or twice should easily allow you to reach the required total of 1,000.