Can be killed with 2 high lvl gigas mate boosted. Our 2 highest gigas have 225% dmg and melt titans in about a minute. Official server.
Just stay away from the back leg stomp as it can enrage a giga quickly due to speed of attack.
Easily killable with a wyvern. Lightning and poison easiest down to longer range in attack. Just hover above and light it up :) killed my first today and it didn't touch me once. Just remember to watch stamina ;)