User blog comment:Pf987/If you were to rework ANY champ not on Rito's radar in any way, what would you do?/@comment-1876049-20151109200357/@comment-26378838-20151110125245

While Teemo and Mundo do indeed resist changes because of their popularity, the issue with Singed is his kit, you'd need Sion-level rework on him and only his flip would survive it. Singed's role as "the guy you don't chase" simply doesn't work in the game, you'd have to make him someone else to balance him.

About Teemo, Season 6 will probably force Riot to rework his E because of the reworked Runaan's Hurricane. With crit chance runes and the fact that Runaan's bolts will be able to crit, he'll be way more infuriating.