I hope you just trolling. They stoped to work on tf.com to start tb tb which is actually small subset of tf.com, and new desing decisions made lot of things worse actually, look for example how arena gameplay got totally ruined, and all those farmville like crap. since when official tetris games move forward? i dont see making tetris games that dons't lag on multicore core multi ghz cpu and gigs of rams as something TOO hard to do, you know.
anyway i don't see how currently we can even think about making tournament on tb arena, there is number of reason why it's impossible:
you can't make 2 players room or you can't make private room
you can't join room you want or play with specific person
you can't turn maps off
i think currently battle 2p seems more suitable for any competition (live version of it that is), but there is still issue, you can't play people far from your rank and if ranks are even bit diffrent autohandicap is forced. but gameplay wise it's almost same as arena, except of bombs instead of real garbage.
anyway both modes will probably end as st-stacking race on high levels so results may be quite suprising.
Tetris Online Poland