In Happy Tree Friends Adventures series, some of the playable characters have a hidden ability that makes them different from each other, thus giving some advantages or disadvantages to a level. Usually, characters like Cuddles are known to be well-rounded, but some others have different abilities. These abilities can be seen clearly starting from the second or third sequel.
A well-rounded tree friend is balanced in all stats, though all of them are rather average. Cuddles has this ability, as well as other possible playable characters.
A tree friend having this ability is swift, fast, and light. Giggles has this ability.
A tree friend having this ability swims faster than other characters without this ability. Toothy, as he's a beaver, has this ability.
Exactly what the ability says, a tree friend having this ability can run very fast, making it easier to cross large gaps by combining the jump and the running speed. Petunia has this ability.
A tree friend having this ability can jump higher than other characters without this ability. It's very useful to reach areas that other characters cannot. Flaky has this ability, and by combining it and the newer special power, she can jump about half the game's screen.
Walking on Ice
A tree friend having this ability is usually mediocre in almost all of the stats, but once the tree friend walks on ice, this ability will ignore the slippery effect, making as if you're walking on a normal ground. Nutty has this ability.
As of HTFA 6 onwards, some characters have this ability despite being well-rounded in movement. A tree friend having this ability will give bigger damage to enemies if he/she uses his/her special power. This ability also makes certain characters' special power hits multiple opponents on 3 ways. Two hidden characters from HTFA 6 have this ability. It is possible that Flippy might have this ability as well, as his appearance as a playable character in an upcoming HTFA spinoff short playthrough preview shows him firing his gun on 3 ways.