Major Problem Boss Fight - Mount Steep!

Hiya everyone,

In this thread specifically, I will be giving information about getting up to the Major Problem boss fight (which is the final part of the main story in Mount Steep), as well as covering through the boss fight itself. I will provide links so you are made aware of how to defeat Major Problem, if you do not already know how. By completing the entire story mode in Mount Steep, you will get decent amounts of rewards and lots of medals as you progress.

In order to make it up to the Major Problem boss fight, you need to begin by completing 4 quests prior to battling Major Problem. You must use the Mouseflies (which you get access to by completing the 4 quests) to access the Boss Gate, which are Mouseflies which you control and fire the Mouseflies at the dried cheese, in order to destroy it and open the Boss Gate. To do all of this, you need to find 4 specific characters that are located around the map and talk to them. When you do, they will offer you a quest. If you accept it, and successfully complete it, by following the instructions that are given to you correctly, you will get a piece of equipment towards the Harmonica (which allows you to use the Mouseflies), and a medal, along with a bunch of coins. There are Mouseflies locations that are scattered around the map, which some can be used to unlock collectibles, by using the Mouseflies, by destroying dried cheese which are hiding hidden collectibles. Look for Tumbleweed Ted located very close to where you appear in Mount Steep - simply look left as soon as you spawn in and he will be there (he will offer you a quest). Also look for a Nightcap in the Steep Mines (named Gilly the Kid, located near the Big Drill) and a Cactus in Rocky Flats (named Exposition Al, near the cabin and near the Steep Mines). When you interact with these characters, they will offer you a quest. If you complete all of them, you will collect all pieces for the Harmonica, which grants access to the Mouseflies, and you will be able to use it to get to the Boss Gate, as well as gather other collectibles, such as Golden Chests.

To get more of an idea on how to complete these quests, go here: https://plantsvszombies.fandom.com/wiki/Mount_Steep

Once you have completed all of these quests and are ready to fight Major Problem, locate the Boss Gate. It is located in the Steep Mines, at the end of a lake of molten cheese. Once you use the Mouseflies to break the dried cheese, platforms will appear which you can use to jump across to the Boss Gate. Not too hard, do not panic. A Mouseflies station is located on one side of the molten cheese lake, the Boss Gate is located on the other. Be cautious of which character you want to play as before you head through the Boss Gate - once you have picked and headed through the Boss Gate, you cannot respawn or change your character, unless you back out, so be mindful of that.

The Major Problem fight involves a few varying phases, but once you understand what you need to do, you should have much less trouble with the boss fight. Note that to trigger the boss fight, there is a Miner Problem which you need to defeat first. To understand how to complete the boss fight itself, go here: https://plantsvszombies.fandom.com/wiki/Major_Problem

My Major Problem Tips!

My personal tips for having an easier time defeating Olds Cool are as follows:

• Keep moving throughout the entire fight, when possible, you are much more likely to dodge his attacks. Most of Major Problem's attacks tend to be slow.
• Characters that have a lot of mobility are great for this fight. At some times, the cheese begins to rise and you must climb up a bunch of platforms before the cheese rises enough and catches up to you. The faster you climb up these platforms, the less chance that you will get vanquished by the rising cheese. After all, cheese is dangerous, if it is molten.
• You need to destroy the lit-up bulbs on Major Problem. Using characters that have good aim will make it easier for you to hit them, sometimes they move around. 
• As the fight progresses, there's less platforms that you can step on. Always try to watch your step. If you fall into the cheese, use an ability that helps you to get out, if you have one. Good survival wins the battle.
• If you have an attack or ability (or even an upgrade) that covers an area and can damage or destroy many of Major Problem's lit up bulbs, use those to your advantage. An example for this is Peashooter or Oak, as he deals splash damage, meaning that if there are a few lit-up bulbs located close together, you can damage them all. Another example is Oak's Super Sap Trap (or maybe even Grody Goop from Chomper, which I don't know how that would go).
• High health characters and/or characters with self-healing capabilities are good to have as you gain increased survivability. Just be careful of the cheese, as always, if you take damage from the cheese multiple times in succession, you will be vanquished and be unrevivable. 
• When Major Problem submerges, make haste and do what is appropriate, depending on why he is submerging, and start climbing the platforms quickly (so you are staying ahead of the rising cheese) or to avoid his attacks that he will fire at you, such as trying to drill you from underneath. 
• Before entering the Major Problem boss gate, consider what upgrades you are going to use.

The Rewards

If you manage to defeat Major Problem, you get all of the following:

• 1,000 XP for the character you used to defeat him, if you do not have the levelling up upgrade.
• "Volcanic Interruption" - a medal you earn for defeating Major Problem.
• The Universal Plant Hat - Queen of Fairies.
• 25,000 coins.
• Other rewards you receive along the way in Story Mode.

If you follow along through the story and complete the quests, and then head to fight Major Problem, you should not find it too hard to claim your bundle of rewards that are waiting for you. I hope that this guide was of some use, and I'll see you next time!

Regards

@TheSprinter85