And i will elaborate, the description in game is notorious for being inaccurate on abilities. I would suggest asking an AI of your choosing to help you understand certain abilities more. Make sure your question is clear and you specify madden 26.
A simple breakdown of gambit: increases the release speed like gunslinger does but by roughly 5%. Gunslinger increases the speed by 15%. And yes, you can stack them.But it would be pretty much pointless on Caleb because of how fast his release is. It also adds velocity like pass lead elite or set feet lead. I'm not positive on the percentage of that one, but I do know you can also stack it and it will increase the velocity more than you would see stacking gunslinger and gambit with Caleb. The AI defenders part is true, but the way the game is coded it works like this:
Gambit says: Set CPU catch chance to zero.
Pick Artist says: Trigger standard premium catching animation.
Madden's physics and animation engine always defaults to the physical animation over an attribute modifier. Because Pick Artist forces a physical animation sequence, the game engine allows the defender to make the play, completely ignoring the passive trait on your quarterback because it is an attribute modifier.