So comparing this to other creatures with dive considering that's essentially what Howl is.
NAME: | Wyrm
| ELEMENT: | Air
| COST: | 4 
| ATK|HP: | 3|3
| Ability Cost | 2 
|
| NAME: | Hellhound
| ELEMENT: | Fire
| COST: | 6 
| ATK|HP: | 5|3
| Ability Cost | 2 
|
|
Well hellhound basically has 4 more attack (due to howl) for only 2 extra quanta so I'd probably either decrease it to 4|3 or increase cost to 7

you're choice.
NAME: | Elite Wyrm
| ELEMENT: | Air
| COST: | 4 
| ATK|HP: | 5|3
| Ability Cost | 2 
|
| NAME: | Fiery Hellhound
| ELEMENT: | Fire
| COST: | 5 
| ATK|HP: | 5|3
| Ability Cost | 1 
|
|
So the upgrade for each, well they're exactly the same but Fiery hellhound costs one more and reduces it's ability cost by one, I'd suggest reducing defense to 1 or 2 hp.
NAME: | Pegasus
| ELEMENT: | Light
| COST: | 4 
| ATK|HP: | 3|2
| Ability Cost | 1 
|
| NAME: | Hellhound
| ELEMENT: | Fire
| COST: | 6 
| ATK|HP: | 5|3
| Ability Cost | 2 
|
|
So if you wanted to make the ability cost only 1 quanta then you can make it have to be used in a duo and gravity might be a good choice but a new name for the ability would be needed, also I think reducing attack to 4 would be good if you wanted to go down this route.
NAME: | Elite Pegasus
| ELEMENT: | Light
| COST: | 4 
| ATK|HP: | 4|4
| Ability Cost | 1 
|
| NAME: | Fiery Hellhound
| ELEMENT: | Fire
| COST: | 5 
| ATK|HP: | 5|3
| Ability Cost | 1 
|
|
So if you were going for the gravity duo I'd think this would be fine but decrease the defense to 2.
Took me a while to do that but it'll help me in future if I need to compare two cards, also remember you need to add the icons in the text section of the image.