That is so cute! I love turtles!
If I find a great planter I get it drainage holes or no. If it's a resin or plastic one a simple drill with an appropriately sized bit takes care of the problem.
Ceramic takes a little more effort. I got a set of diamond tip bits on Amazon that work GREAT! You must have to make sure to keep the spot being drilled wet. They were cheap too! Link below
BLENDX Diamond Drill Bits - Glass and Tile Hollow Core Drill Bits Extractor Remover Tools Hole Saws for glass, ceramics, porcelain, ceramic tile, Pack of 10 https://www.amazon.com/dp/B01MR1HTLH/ref=cm_sw_r_apan_i_D8A6M0FMNPVM42DBV7Y8?_encoding=UTF8&psc=1
As others have said, diamond tip hole saw. Can get a whole set on amazon for 14$. Have this same kit. https://www.amazon.com/BLENDX-Diamond-Drill-Bits-Extractor/dp/B01MR1HTLH/ref=sr_1_3?ie=UTF8&qid=1514315532&sr=8-3&keywords=diamond+hole+saw+kit
Yeah, I bought a decently cheap set on Amazon.