Can You Animate on Nintendo DSi?

Not in any practical sense. The DSi lacks the hardware, software, and input precision for animation production.

CPU: 133 MHz ARM9 + 33 MHz ARM7. Insufficient for raster/vector rendering pipelines.
RAM: 16 MB (shared). A single 256x192 15bpp frame = 96 KB. No room for onion skinning, layers, undo history.
Storage: 256 MB NAND (OS + DSiWare). SD card accessible only via Photo Channel / SD slot (FAT32, slow).
Input: Resistive touchscreen (single touch, low res), D-pad, buttons. No pressure sensitivity, no stylus hover.
Software: Only Flipnote Studio (pre-installed) and Flipnote Studio 3D (3DS only) exist. No DSiWare animation apps were released.

Frame-by-frame, 2 layers (FG/BG), 3 colors (Black, Red, Blue), 128x128 effective canvas.
Export: .ppm (Flipnote format) → SD → PC → Convert to GIF/MP4 via Flipnote Studio 3D (3DS) or PC tools (flipnote.py, ppm2gif).
Online: Sudomemo (community server replacing shut down Hatena). Active community.

Phone/Tablet: FlipaClip, RoughAnimator, Procreate Dreams, ToonSquid. 60 FPS, layers, onion skin, audio, export MP4.
PC: Krita (free), Blender (free), OpenToonz (free), Adobe Animate.
3DS: Flipnote Studio 3D (free, 3D layers, stereo, better UI).

The DSi is a viewer for Flipnotes, not a creator's tool.

Nintendo DS