Enter "Help Me" for your name to start with 10 lives.
Here is the password to start the last level with Trevor and Grant. You do not need to switch to Grant at any point to get the achievement. He just needs to be in your party.
Blank, Blank, Blank, Blank
Whip, Blank, Blank, Blank
Blank, Whip, Cross, Blank
Cross, Cross, Blank, Cross
Be sure to save often and abuse the save feature as much as you can.
When you get to the room with the bridge going left and has 2 of those double headed things shooting fireballs, the 2nd which is by the door has collapsing floors in front of it. I found it difficult to get past without losing a lot of health or dying so I would just let myself get hit while running past it and jumping over it to the door. There is a checkpoint once you enter the next room. It's the only checkpoint of the level. I would let myself die there to respawn again at full health. One of the candles after that will have an axe. I recommend grabbing it and hanging on to it. Save your hearts and don't use it until the final Dracula form.
Dracula form 1:
He will spawn 2 pillars of fire. If you're moving around more, you're more likely to have them spawn farther apart which will give you more room to work. Ideally you want to have the closest one to him spawn close enough that you can reach with your whip. You must hit him in the head. Shortly after the first 2 spawn, another one will spawn under you. It takes a bit to get the timing down as when to move to avoid it. Because of the 3rd pillar of flame is why you want more space to work between the first 2 pillars.
Dracula 2nd form:
He has 5 heads that all need to be destroyed. Good thing about the whip is that it can hit multiple heads in one attack. It'll move back and forth throughout the room. You need to avoid the slime each head drools out any time you're under it. Fortunately the more heads you destroy, the less slime he can drool.
Dracula 3rd and final form:
He's now a big monster and you can to hit his head to damage him. This is where the axe is handy. Jump up and while in the air, throw an axe at his head. There are moving platforms that you can use to get higher and closer to his head if you wish. You just need to avoid getting hit by lightning bolts he emits from his hands.