Gladiator Beasts have always been good but have in recent times come across those problem's of hitting cards like Ryko, Lightsworn Hunter- Gravekeeper monsters- Penguin Soldier's- and all those massive defender's, however now with the new card Viral Mail they may be able to make it back to tier 1. Though we have to wait till Generation force to get it.

Once per turn, you can select 1 face-up Level 4 or lower monster you control. During this turn, the selected monster can attack your opponent directly. At the end of the Battle Phase, send that monster to the Graveyard.
This is going to allow you to bypass all those anoying defensive monsters and Gyzerus them after you attack. What are your oppinion's on the card.

It would be, but which ability will be activated first?

Normally, since both activate at the first time, you can decide on the order this type of cards activate their effects, so it doesn't really matter, GB can return to the deck first to summon another GB, then Viral Mail would activate but sincer there's no monster there anymore, nothing is sent to the graveyard xP

The only problem I see is that its continuous, that means its susceptible to all sorts of things.

The card is amazing. I can get past almost anything front-row related with this out. If I already baited out MSTs, this+Seven tools/Solemn/trap stun = almost guaranteed field control.