Blast Burn may be an incredibly strong fire type move, but with its 90% accuracy and one turn rest time afterward, it can create a big issue where your pokemon could get 1 hit KO'd in that time of respite. Other moves might be necessary that can hit just about as hard with no downtime, there are a number of solutions with different moves that can be taught or are available.
They may not be common, but other 150 attack strength moves are out there and some even stronger, however sometimes a weaker and more accurate move is stronger than one that's a risk to use. So here are 10 alternatives to Blast Burn that are of similar strength.
10 Sacred Fire 100
This Entai/Ho-oh specific move has an attack power of 100, which with no rest time can be used twice in a row for 200 attack power compared to blast burn which can only do 150 over 2 turns. The major benefit of this move is that it will thaw out the user if they are frozen, it's a good surprise counter if someone foolishly uses an ice type against your Entei. With its 95% accuracy, you are most likely going to hit each time making it a worthwhile move to use.
9 Fusion Flare 100
This 100 power move has 100% accuracy, meaning you are guaranteed to hit 200 points of damage on the opponent over 2 turns, making it even better than sacred fire with less accuracy.
For the 5 power points, you can hit all day long, or at least as long as you don't get a sand attack. So long as a sand attack doesn't come, you can hit with this move every time you want to use it. This is another move that's legendary specific with the title pokémon of Black and White taking the throne of Sacred Fire.
8 Flare Blitz 120
With this move, you get both 100% accuracy and 15 power points making it the most reliable and strongest moves so far. The biggest drawback is the user takes recoil damage when the move is used.
For a move 20 attack points higher, of course, it would have to have drawbacks as it would have been one of the strongest moves available if there wasn't risk involved. Most fire type Pokémon can learn this move putting it above the rest as it isn't legendary pokémon gatewayed.
7 Overheat 130
Overheat may severely lower your stats, but over 2 turns can still do over 200 damage. Its risk may lower your stats and leave your pokémon near useless for the battle, but it can still be a devastating move if need be in a desperate situation. With 90% accuracy, there can be a situation where your pokémon can miss a move, which can leave a very dangerous opening, Overheat is another move most fire type pokémon can learn, not just the legendaries.
6 Eruption 150
This move's attack all depends on how high the user's pokémon health is. 150 attack power when the user's pokémon's health is full, but any less and the power goes down. When at full health, this move is just as strong per attack as Blast Burn. Its accuracy is 100% putting it above Blast Burn, however, it's only learned by specific pokémon like the gen 2 fire type starter, Camerupt, and legendaries like Groudon and Entai.
5 Mind Blown 150
This REALLY special move forces the user's pokemon to make its own head explode as an attack. As it can easily be seen, your Charizard is not learning this move as it's the signature move of Blacephalon. this 150 strength and 100% accuracy move out matches blast burn with the ability to use it continuously, but the user's pokémon has to sacrifice half of its health every time it uses it. In case it wasn't a traumatic enough event to have your pokémon's head blow up once.
4 Shell Trap 150
This high damage move is much like a Yu-Gi-Oh! trap card where the user pokémon lays a trap, and if it's hit by a physical move like tackle, the opponent takes this huge damage. This move takes quite a bit of foresight or knowledge of your opponent's moves, plus your opponent has to fall for the said trap and not just keep hitting you with hyper beam. This move can only be learned by Turtonator, so your Squirtle isn't some Pharaoh.
3 V-Create 180
This move can hit with attack damage of 180, but it will generally lower all stats of the pokemon that uses it. This is the strongest regular fire type move available but it's gatewayed by a very certain legendary, Victini. This legendary only move only has 95% accuracy which in pokémon logic means it won't hit every time. With only 5 power points it won't be able to completely lower all the stages of a pokémon's stats when they finish using it, but each use can be a big risk as it will become slightly weaker each time and make Victini more and more vulnerable to attacks and losing the first draw.
2 Wildfire (G-Max)
With your pokémon Giga-maxed its moves change to moves like Wildfire, where the power of the move depends on what move it replaced when G-maxed. In other words, a Wildfire based on Blast Burn will have 150 attack power with no recharge time, while a Wildfire based on V-create will have 180 attack points without any of the stat lowering disadvantages. This move has the potential to be stronger than Blast Burn and also more advantageous than Blast Burn even if that's the strongest move you have available to you. A Wildfire based on Blast burn can be used multiple times, meaning you can hit your opponent with 150 damage with no recharge time, three times maximum before G-max ends.
1 Inferno Overdrive (Z move)
Inferno Overdrive's power is based on the move it's based on much like G-max moves, except with Z moves the power of the move goes up. If Inferno Overdrive is based on V-Create your total attack would be 220, 70 total attack point higher than Blast Burn. The biggest drawback is that you can only use it once per battle, so you have to time this move just right for it to be the most effective. Even if it is based on Blast Burn it will still have 200 attack points, a mere 50 points higher. A z move is the highest power move you can use in one turn making it the strongest move that a fire type can use, even stronger than Blast Burn.