Going off that list KIRA posted... Leavanny is currently Ash's strongest Pokemon, given all the battle's he's won were when he was at a disadvantage. Boldore is tied though with him. Shockingly, Pignite has more loses then Oshawott and Snivy, though that could be because he's battle more then them too
Oh now we know it isn't about number of battles lol.
Proud claimer of Cyndaquil and Ezio Auditore from Assassin's Creed !!
Also proud claimer of Assassin's Creed 2 the game!!