The opening literally says:

Marvel Studios **presents**
a James Gunn film
[names of main stars] Chris Pratt / Zoe Saldana / Dave Bautista
featuring Vin Diesel as Groot
Bradley Cooper as Rocket
[more stars] Lee Pace / Michael Rooker / Karen Gillan / Djimon Hounsou
with John C. Reilly
with Glenn Close as Nova Prime
and Benicio del Toro as The Collector
[even more stars] Laura Haddock / Sean Gunn / Peter Serafinowicz / Christopher Fairbank
[crew credits, starting from Casting not gonna mention them]

The ending credits (after the stinger) says:

Distributed by Walt Disney Studios Motion Pictures

Bulletproof en Revolution something weren't mentioned ANYWHERE in the whole credits. And MPC only for visual effects. Walt Disney is the distributor, so, while it doesn't literally say "a Marvel production" or something, I let Marvel stay x']