Set Default Paste Format In Microsoft Office Products
Solution 1:
For Windows computers:
In Microsoft Office 2010 products and later you can set the default paste options in..
File > Options > Advanced
Scroll down to Cut, copy, and paste and set your desired defaults.
For MacOS:
Office for Mac does not support this function currently. Possibly because MacOS handles copy/paste differently and has its own functions for setting paste defaults.
Open Mac Preferences > Keyboard > Shortcuts
Add a new App Shortcut to each of the Office products with the desired paste settings (such as "Paste and Match Formatting") mapped to Command - V.
Solution 2:
music2myear's answer is still likely the best if you want to override the normal "Paste" command, but there is also an option to do: Command+Option+Shift-V if you want to do the "Paste and Match Style" in Outlook or the equivalent "Paste and Match Formatting" in Word.
Achieving this in Excel and PowerPoint is still a different animal, since as near as I can tell there is not a direct menu option for this in those apps on a Mac.