You will generally find that a maximum Link rating of 70-90 is plenty high enough, so don’t get overworried if a perfect partner for one of your Warriors refuses to show its face. At the same time, if you find that your overall Link ratings are in the high 30s and one of your Warriors is still running around with a Pokemon that has a Link maximum of 39-42%, it’s probably time to seek out a better-suited partner for that Warrior so they can stay useful in battle.
In other words, don’t obsess, but don’t ignore the opportunity to pick up new partners. As a general rule of thumb for myself, at this point I usually pick up a silver-medal rated partner for each Warrior whose partner has a maximum Link of under 50%, so that I can at least be assured that the Warriors will not become useless anytime soon. If I can find a 100% maximum partner, though, I’ll take the opportunity.
The easiest way to do this is to dedicate a month or three just to searching for new partners every two or three cities you take. This gives you a chance to expose each of your warriors in battle to all of the pokemon you can find with a type that matches their Specialty, but isn’t so long as to make you waste hours and hours of extra time on the game. Make sure that you send each Warrior first to a location where Pokemon of their Specialty are most common and then, once they have found a better (or preferably, the perfect) partner, move them to a place where the wild Pokemon tend to be weak to the attacks of their new partner. This not only gives them exposure to a variety of types so they can pick up a partner who will be viable for some time, it also gives them an opportunity to work up their Link ratings with their fresh partners, so they don’t fall behind your army’s overall power curve.
This, of course, also bears mention. Generally speaking, if you’re bringing a batch of Pokemon to the fight where some are more trained than others, you can get away with being up to 10% lower in link rating with the pokemon that have a strong type advantage- that being resistance to many enemy attacks and an attack that many of the opposed Pokemon are weak to. If they only have resistance or their attack is supereffective but they are type-neutral, you should keep them no more than 5% below the average (rough average, you don’t need to do excessive math here) of the group. If for some reason you’re bringing in a pokemon that is weak to the opponent’s attacks or can’t deal much damage thanks to their resistances, either pretend that Pokemon isn’t there when estimating whether or not you can win the battle, or ensure that they’re as much as 10% over the average Link rating for your raiding party. Immunities call for even more drastic variations in power, and generally speaking you can bring a Pokemon that is immune to the vast majority of enemy attacks regardless of what its Link rating is, so long as it can at least deal a little damage.
