Board Thread:Questions and Answers/@comment-29625074-20170221181019/@comment-86484-20170221205813

You can grind for money at the CORE. You can get from 70 to 130 Gold per battle, and if you walk along the bridge that's next to the CORE's last save point, you can have a battle and then go back and save as many times as you want. That was the fastest way to get Gold for me.

As for the fight against Asgore himself, talk to him 3 times before you start FIGHTing. That'll reduce his attack and defense. He will end his turn if you reach 1 HP, so you can put off eating anything until you're down to 1 HP (note: he WILL kill you if you keep fighting when you're at 1 HP). And equipping the Heart Locket will boost your defense, which makes it better than the Apron because you'll lose fewer HP each time you get hit.