WARNING! OBVIOUS SPOILERS AHEAD!
Portal 2's ending
almost made me cry, It was the beautiful music mostly.
100% ending to
Crash Bandicoot. You ride a giant bird with Tawna.
Another Crash one, (OANST is going to love me) The boss fight with N-Gin in Crash 3: Warped was always a favorite when I was a kid.
Fighting Red in
Pokemon Gold/Silver. The music is amazing.
The most tripped out moment in Video Game history.
Zelda: Twilight Princess had so many great moments. In my opinion had one of the greatest endings in gaming.
The boss fight with Zant, I love when games take you back to previous locations like this. He also goes crazy at the end
The final boss fight splits into 4 separate fights, each very,
very epic.