Bidoof, you know them, you love them, it's Bidoof!
A classic HM user with a lot of love to give, Bidoof, and by extension Bibarel, are very solid Pokemon that are more than capable of carrying you through the game, quite literally sometimes. In Diamond, Pearl, and Platinum, Bidoof is a fairly solid early game get, they tend to have mild issues with Roark's rock types but depending on the ruleset you're using, you may very well have a Bibarel by then, who is more than capable of bodying most of what Roark has to offer while also hitting back with super effective Water Guns in return. Bibarel may suffer in usefulness soon after, though, as in the fight against Gardenia, you'd be hard pressed for a use for a Pokemon weak to grass with only neutral coverage options. For Gym 3, things are going to be different depending on what version you're playing, as in Diamond and Pearl, Bibarel is likely hitting the bench with ideally anything that's not weak to fighting coming in, as Maylene does not play around. Bibarel can do some work in Fantina's gym in Platinum, but beware of her Mismagius using Energy Ball, it has nearly perfect coverage and can snipe quite a few Pokemon very unexpectedly. Up next in DP is Crasher Wake, who you at least have a resist against his STABs, but otherwise Bibarel is lacking in any particularly amazing way to damage his Pokemon, especially his lead Gyarados, who will completely body an unprepared Bibarel with Intimidate.