I play intro games normally 1 vs 1 (one of the 1s would be me) with two Mechs per side.
One Mech alone per side doesn't catch BT very well, IMHO.
Different roles, supporting each other, beating the initiative roll, all that is lacking in 1 Mech vs 1 Mech.
My preferred Mechs for newbies: Hunchback + Shadow Hawk.
This covers a lot of ground: jumping, cluster weapons and minimum range for the SH, lack of range, powerfull weapon, tin foil armor on the back for the HB.
I'd play something like an Urbie and a Valkyrie. Enough to teach that Mechs like the HB needs to close fast but also need cover for his back, but not enough to win under normal circumstances AKA The Dice Gods are indifferent.
In your case maybe letting the two newbies playing against each other and you helping both would be the best way.