Please leave the mushrooms off the pizza. My friend Gary hates them. He doesn't like anything green either. We want extra cheese instead, please!

"Gary" is third-person singular (he), so the affirmative verb needs an -s: hates.

For negative sentences with "he", use "doesn't" followed by the base verb without an -s: doesn't like.

"We" is plural, so it takes the base verb: want.