I know it sounds cliché but there's always a counter solution to everything. Instead of going head to head with a stronger team, consider split pushing or pushing kn a separate lane.

And if you wanna risk it, let your carries play dota as usual and farm for core item instead of def too early. My experience is that if you're able to drag the game longer than 30 minutes, its anyone's game. Goes down to who has the better carry and team fights.

If they use global silence or zeus ulti too early in the game, thhen they've wasted gold for when it matters.

Also, you can save your beast in an alternate lane while you focus on teamwipe the enemy. Only after that you tp your beast to join later. Its end game definitely

Agreed with your first point, there isn't a best strat right now.
Obviously, certain heroes benefit from YB event due to its early strength and healing/buff prowess, but a good player can win the event with any hero provided he plays a good game.

Yesterday my party consisting of CM, OM, Riki, Warlock and Slardar had to go up against a very strong lineup of Omni, WW, Jugg, DP and Undying. We were rekt so bad in the early game because their heroes keep healing their YB and pushing our lane easily with DP and Undying skills.

We lost our mid lane in the 20th minute. And that's when the comeback happened.
After their YB was killed, the entire team were left barren with no strong carry. And our team heroes have eventually gained some of our core item.

Eventually, we won every team fights after that. The enemy team also wasted a lot of their AP on zeus ulti and global silence, that by the end of the game, they probably couldn't even afford double damage spell, while we totally rekt their base after every teamwipe and won the game under 40 minutes. A long match by YB event standards.

MORAL:
1- if you know your team is losing lanes early in the game, just drag and let your carry get fat. A perfect example of this is Sniper. He is like your future investment in case that your team is losing steam.

2- while its good to push during YB spawn, always keep to your game objective even when YB isn't around. My team manage to take mid lane without the assistance of YB, and that makes it easier to win in the long run.

3- be willing to let go of your T1 or T2 where you fail the lane. Def at T3 and you should be able to turn the game around as a team.

Its untradeable but its giftable no?
Plus the one who receive the gitft can eventually sell it to market past its restriction date.

Normally my friends exchange sets between each other after every win.

Agreed.
I prefer having Warlock better than Omni.