Trundle is strong, but very Auto Attack heavy with little mobility options. I think Jax, Malphite and Nasus have the best chances to beat him 1v1 post Lv6.
Jax has his Stun and invulnurability to deal a lot of damage without Trundle being able to trade back any meaningful damage.
Nasus has Wither and Stacks do play Whack-A-Troll, if Trundle refuses to get an early Armor Item. I'm also pretty sure, his passive alone can outlast Subjugate if you get to trade on your Spirit Fire.
Malphite is just great for this matchup due to his build-in auto attack slow in his Ground Slam. I know it doesn't sound like much, but he has some other options in his kit and in his buildpath to give Trundle a run for his money.
I thought about Rammus for a while, as I see him in a very similar spot as Malphite is. You just need to stack a ton of armor and ruin his day because Tremors and Defensive Stance deal Magic Damage and he doesn't get much MR out of you. But if he just rushes his Spirit Visage he might plain wreck you instead.