Hi recently I found oyt my infernape can learn hp grass but I'm not sure if he sgould learn it. Currently hes moveset are: Flamethrower Brick break Flare blitz Thunderpuch And his ability is iron fist I would apreciate very much yours advice
No you shouldn't teach it HP Grass unless you're having frequent problems with ground/water types which still isn't the best reason to. You have thunder punch as your water coverage and the ability iron fist to boost that move.
Hope I helped.