Number One:

-Typhlosion
.....Do I need to say anything more? It's a fiery and aggressive Pokémon. The ideal starter for him. And of course, he'd have type advantage over poor ol Izuku.

Number Two:

-Primape
It's a mean, rage fueled, hair trigger tempered, violent fighting monkey. And it's fur looks like Bakugo's hair

Number Three:

-Electrode
The Pokémon known for literally blowing up for funzies

Number Four:

-Houndoom
An aggressive fire/dark type, this super powered Doberman would more than likely have a spot in Bakugo's team

Number Five:

-Arcanine
A powerful fire type(who also has hair similar to him) would be a prime candidate, although I imagine Bakugo had to work hard to earn the Fire stone to evolve him from Growlithe.

Number Six:

-Turtonator
It's highly explosive, and it's a dragon(apparently....)

Honorable mentions:

-Magmortar
A pure fire type that launches blasts out of it's hands

-(shiny)Camerupt
Bakugo could use a mineral type Pokémon. Who could be better than this fire/ground type volcano-camel?