Can Minecraft PE and Minecraft WiiU do multiplayer at all?

No. Wii U version will only do multi-player with other Wii U versions.

For the WiiU, you can only do two player split screen. No online.

Multiplayer is available only when the Wii U console is playing in High Definition mode which requires a HDMI cable or Wii Component video cable connection between the Wii U console and the TV.
Only a Wii U GamePad and Wii U Pro Controller or Wii Classic Controller can be used in multiplayer mode.
The first Player LED on the Wii U Pro Controller will light up when it's synced.
Start Minecraft and at the Main Menu, select "Play a Game" and press the A Button.
Load or Create a game to play.
During gameplay and while the game is playing on the TV, player two will press the +Button on the Wii U Pro Controller to activate multiplayer mode.

To activate multiplayer mode, the game must not be playing on the GamePad exclusively (Off-TV Mode). If playing Off-TV Mode, click the TV Mode icon on the bottom right of the GamePad screen. If done correctly, the GamePad should be displaying a Minecraft block.

Player two will select a character and press the A Button.
The game screen will switch to split screen and multiplayer mode will begin.

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PE I think only has local multiplayer, accessed through the top roight menu by selecting servers.

I'm afraid not. You will need to get a pro controller for the Wii U. One of you use the pro controller, the other uses the gamepad. You can do split screen multiplayer on the TV, or have one screen each. One person uses the TV screen, the other uses the gamepad screen.