I'm still leading with Jerome the Clockwork Gnome - getting two towers up, healing when possible, withdrawing after ressurection, he usually subdues the opposition sufficiently to let the curious wolver pup and creepy crate finish them off. I especially enjoy the crate's ability to force the lowest health opponent into battle.
That said, because Jerome was 16 and the other two only 10, to go up against wild tamers I took to capturing pets in their areas to get the levels I needed. Jerome is currently teamed with a rare scorpid and an uncommon water snake, who are holding their own.
I've a handful of comedy teams at lower levels, for variety. The tiny snowman, tiny harvester and tiny spore bat fight as Wilson, Kepple & Betty, respectively (ask your grandad). The rare fawn and rare rabbit team with the achievement skunk as Bambi, Thumper and Flower (they're a surprisingly effective team - the skunk lowers the opposition hit chance, the rabbit packs a punch and Bambi has good survivability. I'm still looking for a rare skunk). Wynken, Blynken and Nod are, naturally, Willy the orphan reward, the pink elephant from brewfest and the the perky pug achievement reward. None of them are disasterous teams, though they weren't chosen for their abilities or compability.