Well it was both CIS/PIS imo either way I don't know of anyone other than Bats to use tear gas. Most of Grundy's opponents use battle field removal to stop him if they can.
Grundy vs Hourman, Dr. Fate and GL Alan. He one shots Hourman who remains koed for a couple of panels. Dr. Fate tries to freeze and electrocute Grundy to no avail. Grundy simultaneously double ko Hourman and Fate. He survived the vacuum of space for a while to make it back from being imprisoned on another planet by GL. Grundy controls wooden objects and ultimately kos GL. Then he returns to the swamp and turns him into a zombie.
In Justice League of America #4-#6. a highly intelligent and sophisticated Grundy emerges serving as the brains behind a complex operation to willingly transfer Professor Ivo's immortality to Grundy, so he would no longer need to be resurrected. Grundy one-shots Red Tornado for a couple of panels and verbally own Red Arrow. Later, Grundy and Red Tornado who is in a human body fight, and Grundy breaks his hand and eats it.
An unarmed Cyrus Gold escapes capture and kills multiple armed guards while having a huge hole in his chest. He also survives getting impaled by a decaying tree after jumping off a helicopter.
Great regeneration feats. Grundy easily withstands an onslaught of rapid fire gunshots and regrows his hand after the Bride shot it off. Then he regrows his entire head after Frankenstein shot it completely off.
Awesome durability feat. As Grundy was breaking through GL Alan's shield, Frankenstein stabs him through his chest with a holy, magical weapon, sword of Michael. Grundy survives the resulting huge explosion that destroyed the swamp.
Grundy vs Bizarro, Manbat, Young Frankenstein and his Bride. Regrows his head again and rips out Frankenstein's heart, before being speedblitz into the sun by a bloody Bizarro.