Thanks, more idea:

20. Culture Shock:

You have to perform something big for the talent show.

21. F.U.N:

Foil another one of Plankton's plans

22. MuscleBob BuffPants:

You have to try to make Spongebob stronger for the contest.

23. Squidward the Unfriendly Ghost:

You have to escape the bubble before it pops and the seagulls get you

24. The Chaperone:

You have to engage in a Dance Off between someone

25. Employee of the Month:

You play as Spongebob and you battle Squidward to be official Employee of the month

26. Scaredy Pants:

You have to scare 10 people in under 5 minutes. They're obstacles in the course

27. I Was a Teenage Gary:

No idea, maybe you try to turn back into your old self

28. SB-129:

Squidward, and you have to get back to the Krusty Krab

29. Karate Choppers:

You battle Sandy and have to win

30. Sleepy Time:

You have to do a small mission in each dream {like for Pearl you have to find a missing stuffed animal}

31. Suds:

You play as Sandy to try to get Spongebob to the hospital

32. Valentine's Day:

Not sure, maybe help Patrick in someway

33. The Paper:

Not sure, see how annoying you can be?

34. Arrgh!:

Hunt for treasure

35. Rock Bottom:

You have to escape Rock Bottom in a certain time allowed

36. Texas:

Help Sandy overcome her homesickness.

37. Walking Small:

Thwart Plankton's plot to turn the beach into his shop.

38. Fools in April:

You play as Spongebob, and you and Squidward play pranks on each other. More of a fun level.

39. Neptune's Spatula:

Beat Neptune.

40. Hooky:

You have to convince Patrick to let you go to work. Or you get caught on a hook and someone has to save you.

41. Mermaid Man and Barnacle Boy II:

Defeat the dirty bubble.

42. Your Shoe's Untied:

Learn to tie shoes and teach Patrick how to.

43. Squid's Day Off:

You're Spongebob in charge of the Krusty Krab for the day.

44. Something Smells:

You have to defeat enemies with your nasty smell.

45. Bossy Boots:

You have to "battle" Pearl

46. Big Pink Loser:

You, as Patrick, has to win something.

47. Bubble buddy:

You have to help your Bubble Buddy survive the wrath of Bikini Bottom

48. Dying for Pie:

Give Spongebob his perfect last day only for him to survive.

49. Imitation Krabs:

There are two Krabs. One is real, one is Plankton. Figure out which one is Plankton.

50. Wormy:

Protect Bikini Bottom from the "monster"

51. Patty Hype:

Sell as many pretty patties you can in the time allowed

52. Grandma's Kisses:

You have to escape Grandma Squarepants' house before she catches you and kisses you.

53. Squidville:

Find the real Squidward.

54. Pre-Hibernation Week:

Do all things Sandy wants to. But you can get hurt and die, so be careful.

55. Life of Crime:

Run from the law, turn yourself in, get outta jail quickly.

56. Christmas Who?:

Spread Christmas Cheer!

57. Survival of the Idiots:

The whole level you have to survive from Sandy, who thinks you are Pinhead Larry and Dirty Dan.

58. Dumped:

Convince Gary you need him more then Patrick does.

59. No Free Rides:

Try to stop Mrs. Puff from stealing your boat.

60. I'm Your Biggest Fanatic:

Hunt and Capture the King Jellyfish

61. Mermaid Man and Barnacle Boy III:

Fight Manray.

62. Squirrel Jokes:

Don't know, maybe tell non-squirrel jokes or face Sandy's wrath.

63. Pressure:

You play as Spongebob, Patrick, Squidward and Krabs and outdo Sandy.

64. The Smoking Peanut:

Find out who threw the peanut.

65. Shanghaied:

Obey Flying Dutchman

66. Gary Takes a Bath:

Force Gary to bathe with the time allowed

67. Welcome to the Chum Bucket:

Escape Chum Bucket in time allowed

68. Frankendoodle:

Fight the doodle Spongebob made of himself.

69. The Secret Box:

Find out what is in the secret box.

70. Band Geeks:

Play for Squidward and make him proud

71. Graveyard Shift:

Survive the Graveyard Shift... by yourself!

72. Krusty Love:

Help Krabs "woo" Mrs. Puff

73. Procrastination:

Don't work on your project, but try a little

74. I'm With Stupid:

Convince Patrick's "parents" he's a genius.

75. Sailor Mouth:

Try not to swear. When Patrick does, try to tell Krabs before he tells on you first.

76. Artist Unknown:

Teach how to make sculptures

77. Jellyfish Hunter:

Save the jellyfish from Krabs

78. The Fry Cook Games:

Beat Patrick in the fry cook games.

79. Squid on Strike:

Play as Squidward and get your job back no matter what

80. Sandy, SpongeBob, and the Worm:

Hunt the worm and beat him down.

Thoughts?

nice ideas!

More of mine, continuing in order:

81. The Algae's Always Greener:

You have to stop Krabs {because he is technically "evil" in this one}.

82. Spongeguard on Duty:

Larry the Lobster leaves you in charge of the lifeguarding duty for the day, and you need to make sure nothing happens

83. Club Spongebob:

You need to find your way back home

84. My Pretty Seahorse:

You have to get rid of your horse before Mr. Krabs sees

85. Just One Bite:

You have to battle Squidward in a krabby-patty eating contest

86. The Bully:

You have to fight Flats the bully, the enemy of the level

87. Nasty Patty:

The health inspector is an actual zombie and you have to fight him

88. Idiot Box:

Patrick and Spongebob go to sleep and their box is missing, you {as Spongebob} need to find it

89. Mermaid Man and Barnacle Boy IV:

After making everyone small, instead of shrinking yourself, you have to make everyone else big again

90. Doing Time:

You, as Mrs. Puff, have to escape jail. The prison guards are the enemies

91. Snowball Effect:

You, as Spongebob of course {whenever say you, I probably mean Spongebob} have to beat Squidward in a snowball fight

92. One Krab's Trash:

You, as Krabs, have to find the hate in the graveyard

93. As Seen On TV:

Not really sure... maybe you have to decide if you like being an actor...

94. Can You Spare A Dime?:

You have to search the Krusty Krab for the dime

95. No Weenies Allowed:

You tag team the guard to the Salty Spitoon and his friend. You play as Spongebob but you also get to use Sandy

96. Squilliam Returns:

You, as Squidward, has to convince Squilliam you own the restaurant

97. Krab Borg:

You, as Spongebob, battle an evil Krabs Robot. Then you wake up and it was a dream level.

98. Rock-a-Bye Bivalve:

You, as Spongebob, has to save the baby scallop from falling multiple times

99. Wet Painters:

You have to paint the house as fast as you can without making any mistakes.

100. Krusty Krab Training Video:

No idea... 101. SpongeBob's House Party:

You have to throw the hottest party ever!

102. Chocolate with Nuts:

Sell as much chocolate as you can before time runs out. You have to sell a minimum of 20 bars in 8 minutes. Watch out for the crazy guy yelling "CHOCOLATE!" or you lose

103. Mermaid Man and Barnacle Boy V:

You play as Mermaid Man and have to defeat Barnacle Boy

104. New Student Starfish:

You play as Patrick, following Spongebob to school. But you get lost from him, and you run into a bully and have to beat the bully and find Spongebob again

105. Clams:

You have to find the millionth dollar

106. Ugh:

You, as caveman Spongebob, fight a dinosaur

107. The Great Snail Race:

You, as Gary, need to win the race.

108. Mid-Life Crustacean:

You, as Krabs, need to do 3 things to make you feel like a kid again.

109. Born Again Krabs:

You, as Krabs, need to do 3 good deeds

110. I Had an Accident:

You, as Spongebob, need to defeat the gorilla

111. Krabby Land:

You, as Spongebob, working wit Krabs, design your own Krabby Land for children

112. The Camping Episode:

You, as Swuidward, need to fight the sea bear

113. Missing Identity:

You, as Spongebob, need to find your ID

114. Plankton's Army:

You, as Krabs, need to use different weapons to defeat Plankton's family members

115. The Sponge Who Could Fly:

You, as Spongebob, need to fly and help 4 people with any problem they need help with

116. SpongeBob Meets the Strangler:

You need to put the strangler back in jail

117. Pranks a Lot:

You, as Spongebob, turn invisible with Patrick, and must scare at least 10 people

Ideas? Thoughts?

The goal for the overall game? Hm, maybe something simple like beating Plankton or something. Like maybe each level had stars or keys you need to find to stop Plankton in the final level.

Is that what you meant?

The first post says you get to play through each level

For A pal For Gary, maybe you could play as Gary and have to fight that pet thing Spongebob bought. Though that level would be really hard.

In Keep Bikini Bottom Beautiful, maybe you have to battle Squilliam in about a 10-minute level to see who can pick up more trash or something