Are greninja decks any good competitively after rotation?

supa_malo

I am new to the tcg, me and my gf have been trying to get into the tcg as we have been collecting cards and we both want decks of our fav pokemon mine being greninja and i thought that radient greninja would be an extremely good support card until i learnt he wasnt legal to play so what else do i do as i use really want to use a greninja deck and should i use the terra greninja or just the ex from the battle deck i am really lost please help. Thank you