Ninja's Majestic Hall of Sprites

[TheoreticalSelkie]

Personally I feel like it's more of a disguise than a fusion since it doesn't look too much like a mix between Ferrothorn and Forretress to me, and more like a Forretress with elements of Ferrothorn instead. I like how clean it is.

Wish there was a bit more contrast between your middle gray shade and your highlight color since I didn't notice it until I looked at it more closely in my pixel art program. The contrast between the middle shade and the shadows are fine in my opinion. Also you did have an anti-alias color which was barely noticeable at regular view. If they're too close together you may just be better off combining that and the highlight color.

For your other sprites, I really like Mr. Watch and Grumbone, looks great for fusions (though I'm no good at them myself so I can't really critique much about them right now).