The Giant Enemy Dinosaur is really easy. Just beat him and you'll get the achievement.

For this one, go to the giant enemy dinosaur boss. Next beat him until a raptor (or multiple raptors) spawn. Wait for the raptor to shoot it's laser at you, and then reflect it onto the giant enemy dinosaur. Do this three times and you'll get the achievement.

For this one, go to the target area of the game. Find the mushroom with horns (and the one next to it with a heart). Hit both three times. You should get the achievement AND unlock something special in the pause menu. Enable it and find out what it does (I haven't done it yet).
Massive props to Torny, check out their video and also Merpo https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=2594732293. I wouldn't have found this achievement if it wasn't for their guides.