There is a small indication on the ground. Before the lightning strike, there will be a small white line on the ground. Dodge that and shoot the plant boss. Repeat until you win
You can go to the “LocalLow” file. If you don’t know how to get there, use google. There, you will see a file named “jashinn” or sth. Click that and select the save you want to change. Open it and find sth with rifle. Put the number you want in and save. Reload the save