Please excuse the highlighting. We forgot to close our search after we located these asks. —LH
Pokémon are rarely (practically never) aggressive for no reason, especially if they previously weren’t, readers. Before anything, it’s imperative to figure out why your pokémon are suddenly displaying the behaviors you’ve described, then work to correct the problem from the root. Observe your pokémon to see if you can find any possible triggers. Communicate with them if you can. Consider taking them to a pokémon center to see if their changes in behavior have physiological roots or to receive more personalized care.
Without knowing that root cause, it’s difficult to offer advice, as each of the possible causes come with wildly different solutions, including avoiding certain situations or places (if your pokémon are precognitive, as absol may be—or if they’re simply reading emotions in the case of gardevoir or remembering past traumas in the above ninetales’s case), more rigorous training (if it’s a simple behavioral problem in one or more of the above cases), or even antibiotics or surgery (if the problem is physical in nature). Thus, all I can say is consult your local pokémon center for treatment options, but also, be vigilant in your observations and keep your pokémon’s poké balls on hand at all times.
Lastly, of course, if your pokémon are suicidal, please also be as supportive as possible. Get them the help they need, yes, but also make sure they understand you care deeply for them and will do anything you can to help them.
Best of luck, everyone!
The Pokédex According to Bill 