It’s important to note that this isn’t simply anger but rather aggression born from fear. The importance of this distinction is simple: if it were simply anger, then all you would need is to teach your kommo-o calming techniques. However, because there is clearly an element of fear to its behavior—or at least I gather that there is, judging by its reason for being aggressive towards a particular species—then you would need to address that fear specifically.
Granted, yes, it’s also important to help your kommo-o deal with its aggression in a positive manner by training him to calm on command (Tip: Use positive reinforcement to teach your kommo-o to heel. Reward your kommo-o each time you tell it to heel and it sits or otherwise remains still. Combine this with extra training to let out pent-up aggression), but that’s simply step one of a longer process.
Once your kommo-o learns how to heel and calm itself in high-stress situations, you’ll need to begin exposure therapy. It may be worth it to catch or breed your own wimpod to give your kommo-o regular exposure and thus consistent training; otherwise, set up a regular schedule with your friend. Either way, have your kommo-o interact with a wimpod in a comfortable setting. Begin with a short time period (and have the wimpod’s poké ball in hand) and be firm and quick about heel commands. Also be sure to reward kommo-o every time it holds back instead of outright attacks wimpod to reinforce the idea that it can have positive interactions with members of the wimpod line.
You’ll notice that I avoid telling you to help your kommo-o train and defeat a golisopod. While some trainers prefer doing this, the truth is that this avenue carries a lot of risks. It could help your kommo-o get over their latent fear of the wimpod line, yes … but it could also teach your kommo-o that wimpod and golisopod are easy to bully. It’s far safer to promote positive interactions and to help your kommo-o master its aggression.
Best of luck, anonymous!