Thanks all for your replies. The problem isn't 1v1, its a headache in team games
although in team games, at least one german player goes elephant by default, like at least one sov player goes for isu by default.
in 2v2+, i feel winning tank battles before the isu/ele come out WITHOUT LOSING your own tanks is very crucial.
i know its quiet obvious but what usually happen (in successful games where it is really tight) for my team and me is we just keep massing tanks on top of tanks while the enemy team kept bleeding their own tanks. then when we reach critical mass, probably about 10 - 20 min after we said "f*ck they got isu/ele" (there seems like at least 2 isu/elein tight 2v2+ and 3 isu/ele in tight 3v3+) and we go for a big flank(at least knowing where enemy ele/isu are) in force while isu/ele get in ready to snipe from the front with paks and infantries to secure our own sniping tanks from flanks and counter attacks.
what happens next is that enemies' tanks aren't in position, isu/ele turn around, and f-ed up pathing goes in to full effect. this means that either flanking tanks or sniping tanks are shooting at the ass of enemies' sniping tanks. and then you move up your ele/isu and support the flanking tanks.