Tryndamere will look to split push during the mid-game and he’ll rarely join team fights. You can use the numbers advantage to force objectives or look for favourable fights to gain an advantage.
If Tryndamere is split pushing in the bottom side in the mid-game, avoid sending lots of people to stop him when Baron’s up. It will take you some time to kill him even if you commit 5 champions to kill him which could give his team lots of time to take the Baron.
Try to fight when Tryndamere doesn’t have his Ultimate up. This will make it incredibly difficult for him to dish out lots of damage in a team fight.
Keep the minion wave closer to your side of the map in the early game. Tryndamere has lots of kill pressure and if you push, he could easily all-in you and chase you down the lane.
Look for fights when he has little Fury in his resource bar. The more Fury he has, the stronger he will be.
Whenever his Ultimate R is down, try to abuse the cooldown and look for kills. Once his Ultimate R is up, his kill pressure and survivability increases a lot.
If Tryndamere has Ignite, expect him to play aggressive and look for an all-in at level 2 or 3.
Once Tryndamere hits level 6, his survivability increases a ton. Avoid committing to fights with him when his Ultimate R is up unless you can easily beat him in a skirmish.
Tryndamere is really good in the late game and will look to constantly split push and take objectives. Do not let him take your towers for free while you skirmish in the mid lane.