Well, since the Leopard 2A5 and the Abram M1A2 uses the same Rheinmetall 120 mm gun at 44 caliber length... they can use the M829A3 is the latest american round, and DM63 for Germany.
The Leopard 2A6 and Black Panther uses the Rheinmetall 120 mm gun at 55 caliber length; which can use the M829A3 and DM63 I think.
The Challenger 2 uses a different rifled gun, 120mm L30 at 55 caliber long, which uses the Charm 3 L27A1 as the kinetic penetrator, and L31 HESH
In anycase, take penetration data with a grain of salt, all is classified.
Also, in any Indo-Pak war, there is no way that an Armor division from China or India can cross the Himalayas without being reduced to dust by air power - like afghanistan for soviet armor columns. So it is not likely to happen.