A place for those who "Trust the Fungus"

Was Koopa's 80% devolution supposed to happen alot earlier in the film? You know when his face looked more like the T-Rex he evolved from? (There is a pic of it somewhere on the main site.)

Also the advertisements and merchandise also suggested that....

I doubt it. It would have been really cool, but even with deleted scenes there'd be continuity error. If there were such scenes, they'd be so different as to basically be an alternate last 30 minutes. I seriously doubt such footage exists, except maybe in scraps.

I wonder if all the merchandise and stuff showing him in his T-Rex state was to help win over some ppl who were worried Koopa was just Dennis Hopper throughout the whole movie.

I wouldn't read too deep into it but it looks like Koopa's de evolved state starts showing after Mario and Luigi briefly have him in the chair. Maybe certain emotions kept triggering it. Well first his eye, then later his tongue and forehead.

Likely though Koopa's likely to look cooler on merchandise as the T-Rex rather than a likeness of Dennis Hopper.