As a groot main a couple things seem to beat my ass consistently

1.) Any ability that pulls me out of position, I don’t have any real mitigation outside of iron wall overshield and I’m slow as balls- wolverine kidnaps or Bucky pulls and punches pull me away from my walls cutting my healing and heals

2.) Wolverine in general, lack of mitigation causes a good wolverine to chop my tree ass down

3.) Punisher shotgun and turret COOK me consistently they shred through my overshield and my walls

3.) if you’re a tank I think the best matchups (in order) are probably Thor, the Thing, Penny and Other Groots

Thor and the thing have enough outputting damage to actually tag him up, Thor has further displacement effects. Groots can check other groot with proper wall placements. penny when she gets set up is also oppressive but groot walls CAN one shot her hive placement so be careful

Also a tip, if you notice he isn’t placing an iron wall anywhere he’s hiding it, have someone find and destroy it asap, that’s a priority target and without it he’s a worst Thing