These different coloured dinosaurs in mario games called yoshis are a big help in certain levels. They can defend you by eating enemies like goombas,octoombas and koopas.
yoshi eggs
Yoshi eggs  are white with spots of the colour of the yoshi inside. In some games like super Mario flash 2 yoshi eggs are in mystery boxes and they hatch into yoshis automatically after you jump under the mystery box but in some games with only one yoshi called Yoshi like super Mario galaxy 2 you need to jump on the egg to hatch Yoshi.

yoshi colours
As mentioned in the first paragraph,yoshis are different colours.Yoshi is a green yoshi and Mario's helper,some of the other yoshi colours are blue,pink,yellow and red.

Yoshi is a green yoshi who helps Mario and Luigi complete the levels when he is in them.He is the only yoshi who has his name in the titles of some mario games like Yoshi's Island and Yoshi's Cookie,Yoshi's Story and Yoshi's Minigames.

Click here to read more about Yoshi

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