Shadow Typhlosion

Shadow Typhlosion is actually pretty good. It's a strong Fire Type attacker that has the potential to stand out above many other Fire Types thanks to a combination of Shadow boost, Incinerate, and Blast Burn.  It's not the best, but it's definitely good.

Best PvE Offensive Moveset

• Incinerate is superior to Ember, and is recommended to fulfill a Fire-type role. However, Ember is easier to dodge with. If used in Party Play, Ember will also charge up Party Power more quickly.

• Shadow Claw has fun uses against Ghost and Psychic types, but it’s far from optimal.

• Blast Burn, Shadow Typhlosion’s exclusive Community Day move, is the ideal Fire Type move. 

• Overheat is the next best option, and outclasses Fire Blast in every way.

• Solar Beam and Thunder Punch’s lack of STAB renders them underwhelming.

Best PvE Defensive Moveset

• Incinerate is the best for defense due to its incredible base damage, not to mention STAB. It pairs best with Thunder Punch thanks to its counter-coverage and low energy cost. 

• Shadow Claw is favored over Ember; both have identical defensive DPS, but the former has neutral coverage.

• Blast Burn is generally worth considering defense due to it being a 2-bar move and high power, but it's definitely behind Thunder Punch most of the time.. 

• Solar Beam is very slow on defense, but has coverage against Water, Rock, and Ground.

• Overheat is superior to Fire Blast in all aspects, but neither offer additional coverage options.

Incinerate is a very slow 5 turn fast move, but its greater energy gains compared to Ember are needed for Typhlosion's costly charge moves. Shadow Claw lacks STAB, but it can offer neutral damage when Fire-type attacks would typically be resisted, in addition to having a significantly faster animation than Incinerate. 

Blast Burn is one of the main features of Typhlosion, being one of the most powerful charge moves for PvP, but 50 energy cost isn't that cheap. If you don't have access to Blast Burn from Community Day, it's probably best to choose another Pokemon. Thunder Punch is Typhlosion's cheapest Charged Attack and provides it with coverage against Water-type Pokemon. Solar Beam is the only other consideration for Typhlosion since Blast Burn outperforms Fire Blast and Overheat. With an insanely high 80 energy requirement, you might not even use Solar Beam at all.